Port 993 open but "no peer certificate available" during SSL handshake

I’m facing a problem with my email server setup:

Environment:

  • OS: Ubuntu 22.04.5 LTS
  • Dovecot: 2.3.16 (7e2e900c1a)
  • Managed via HestiaCP
  • OpenSSL: system default

Problem:
When testing the IMAPS connection (port 993) using:

bash

CopiarEditar

openssl s_client -connect mail.minenge.com.br:993

I get the following output:

yaml

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CONNECTED(00000003)
write:errno=104
---
no peer certificate available
---
SSL handshake has read 0 bytes and written 321 bytes
---

What I have verified:

  • systemctl status dovecot shows “active (running)”.
  • Port 993 is open (netstat and ss confirm it).
  • inet_listener imaps (port 993) is configured with ssl = yes in 10-master.conf.
  • SSL certificate (.pem) and key (.key) are valid (openssl x509 and openssl rsa tests succeed).
  • ssl = required, ssl_min_protocol = TLSv1.2, and ssl_cipher_list = PROFILE=SYSTEM are set in 10-ssl.conf.
  • No new errors appear in /var/log/dovecot.log or journalctl -u dovecot after restarting.

Steps I have already tried:

  • Regenerated SSL certificates manually.
  • Reconfigured SSL parameters and listeners.
  • Adjusted file permissions for certificates and keys.
  • Reinstalled openssl, libssl3, and all dovecot-* packages (apt install --reinstall).
  • Fully restarted Dovecot after each change.

What I suspect:

  • The OpenSSL libraries or the system’s SSL context may be broken for Dovecot.
  • Dovecot binds to TCP 993 but silently fails to initialize SSL context.

Question:
What could prevent Dovecot from initializing SSL context properly on port 993, even with valid certificates and correct service configurations?
Is there any extra configuration required on Ubuntu 22.04 or Dovecot 2.3.16 to force SSL context initialization successfully?

Any help would be greatly appreciated!

Show the output of this command:

cat /etc/dovecot/conf.d/domains/minenge.com.br.conf

root@painel:~# cat /etc/dovecot/conf.d/domains/minenge.com.br.conf
local_name mail.minenge.com.br {
ssl_cert = </home/Minenge/conf/mail/minenge.com.br/ssl/minenge.com.br.crt
ssl_key = </home/Minenge/conf/mail/minenge.com.br/ssl/minenge.com.br.key
}

That’s ok.

And this?

 grep domains /etc/dovecot/dovecot.conf

root@painel:~# grep domains /etc/dovecot/dovecot.conf
!include_try conf.d/domains/*.conf

Looks fine. If there are no errors in logs, I don’t know what’s going on.

You could try to add again the right conf for Hestia:

tar zcf /root/backup-etc_dovecot-2025-04-28.tar.gz /etc/dovecot
cp -rf /usr/local/hestia/install/common/dovecot /etc/
rm -f /etc/dovecot/conf.d/15-mailboxes.conf
chown -R root:root /etc/dovecot*
touch /var/log/dovecot.log
chown -R dovecot:mail /var/log/dovecot.log
chmod 660 /var/log/dovecot.log

I believe that recovering the backup is not an efficient task, as the server has been around for months, however the first email accounts were only configured now.

In my log this error is recurring:
imap-login: Error: Failed to initialize SSL server context: Can’t load SSL certificate (ssl_cert setting): error:0A00008B:SSL routines::unknown command: section=system_default, cmd=system_default, arg=hestia_openssl_sect

Looks like a wrong configuration in /etc/ssl/openssl.cnf file:

Show the output of this command (when you copy and paste here, select the copied text and click on button </> or Ctrl+E to format the output).

grep -Ev '^#|^$' /etc/ssl/openssl.cnf
root@painel:~# grep -Ev '^#|^$' /etc/ssl/openssl.cnf
HOME                    = .
 # Use this in order to automatically load providers.
openssl_conf = openssl_init
config_diagnostics = 1
oid_section = new_oids
[ new_oids ]
tsa_policy1 = 1.2.3.4.1
tsa_policy2 = 1.2.3.4.5.6
tsa_policy3 = 1.2.3.4.5.7
[openssl_init]
providers = provider_sect
ssl_conf = ssl_sect
[provider_sect]
default = default_sect
[default_sect]
[ ca ]
default_ca      = CA_default            # The default ca section
[ CA_default ]
dir             = ./demoCA              # Where everything is kept
certs           = $dir/certs            # Where the issued certs are kept
crl_dir         = $dir/crl              # Where the issued crl are kept
database        = $dir/index.txt        # database index file.
                                        # several certs with same subject.
new_certs_dir   = $dir/newcerts         # default place for new certs.
certificate     = $dir/cacert.pem       # The CA certificate
serial          = $dir/serial           # The current serial number
crlnumber       = $dir/crlnumber        # the current crl number
                                        # must be commented out to leave a V1 CRL
crl             = $dir/crl.pem          # The current CRL
private_key     = $dir/private/cakey.pem# The private key
x509_extensions = usr_cert              # The extensions to add to the cert
name_opt        = ca_default            # Subject Name options
cert_opt        = ca_default            # Certificate field options
default_days    = 365                   # how long to certify for
default_crl_days= 30                    # how long before next CRL
default_md      = default               # use public key default MD
preserve        = no                    # keep passed DN ordering
policy          = policy_match
[ policy_match ]
countryName             = match
stateOrProvinceName     = match
organizationName        = match
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional
[ policy_anything ]
countryName             = optional
stateOrProvinceName     = optional
localityName            = optional
organizationName        = optional
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional
[ req ]
default_bits            = 2048
default_keyfile         = privkey.pem
distinguished_name      = req_distinguished_name
attributes              = req_attributes
x509_extensions = v3_ca # The extensions to add to the self signed cert
string_mask = utf8only
[ req_distinguished_name ]
countryName                     = Country Name (2 letter code)
countryName_default             = AU
countryName_min                 = 2
countryName_max                 = 2
stateOrProvinceName             = State or Province Name (full name)
stateOrProvinceName_default     = Some-State
localityName                    = Locality Name (eg, city)
0.organizationName              = Organization Name (eg, company)
0.organizationName_default      = Internet Widgits Pty Ltd
organizationalUnitName          = Organizational Unit Name (eg, section)
commonName                      = Common Name (e.g. server FQDN or YOUR name)
commonName_max                  = 64
emailAddress                    = Email Address
emailAddress_max                = 64
[ req_attributes ]
challengePassword               = A challenge password
challengePassword_min           = 4
challengePassword_max           = 20
unstructuredName                = An optional company name
[ usr_cert ]
basicConstraints=CA:FALSE
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer
[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
[ v3_ca ]
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid:always,issuer
basicConstraints = critical,CA:true
[ crl_ext ]
authorityKeyIdentifier=keyid:always
[ proxy_cert_ext ]
basicConstraints=CA:FALSE
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer
proxyCertInfo=critical,language:id-ppl-anyLanguage,pathlen:3,policy:foo
[ tsa ]
default_tsa = tsa_config1       # the default TSA section
[ tsa_config1 ]
dir             = ./demoCA              # TSA root directory
serial          = $dir/tsaserial        # The current serial number (mandatory)
crypto_device   = builtin               # OpenSSL engine to use for signing
signer_cert     = $dir/tsacert.pem      # The TSA signing certificate
                                        # (optional)
certs           = $dir/cacert.pem       # Certificate chain to include in reply
                                        # (optional)
signer_key      = $dir/private/tsakey.pem # The TSA private key (optional)
signer_digest  = sha256                 # Signing digest to use. (Optional)
default_policy  = tsa_policy1           # Policy if request did not specify it
                                        # (optional)
other_policies  = tsa_policy2, tsa_policy3      # acceptable policies (optional)
digests     = sha1, sha256, sha384, sha512  # Acceptable message digests (mandatory)
accuracy        = secs:1, millisecs:500, microsecs:100  # (optional)
clock_precision_digits  = 0     # number of digits after dot. (optional)
ordering                = yes   # Is ordering defined for timestamps?
                                # (optional, default: no)
tsa_name                = yes   # Must the TSA name be included in the reply?
                                # (optional, default: no)
ess_cert_id_chain       = no    # Must the ESS cert id chain be included?
                                # (optional, default: no)
ess_cert_id_alg         = sha1  # algorithm to compute certificate
                                # identifier (optional, default: sha1)
[insta] # CMP using Insta Demo CA
server = pki.certificate.fi:8700
path = pkix/
recipient = "/C=FI/O=Insta Demo/CN=Insta Demo CA" # or set srvcert or issuer
ignore_keyusage = 1 # potentially needed quirk
unprotected_errors = 1 # potentially needed quirk
extracertsout = insta.extracerts.pem
ref = 3078 # user identification
secret = pass:insta # can be used for both client and server side
cmd = ir # default operation, can be overridden on cmd line with, e.g., kur
subject = "/CN=openssl-cmp-test"
newkey = insta.priv.pem
out_trusted = insta.ca.crt
certout = insta.cert.pem
[pbm] # Password-based protection for Insta CA
ref = $insta::ref # 3078
secret = $insta::secret # pass:insta
[signature] # Signature-based protection for Insta CA
trusted = insta.ca.crt # does not include keyUsage digitalSignature
secret = # disable PBM
key = $insta::newkey # insta.priv.pem
cert = $insta::certout # insta.cert.pem
[ir]
cmd = ir
[cr]
cmd = cr
[kur]
cmd = kur
oldcert = $insta::certout # insta.cert.pem
[rr]
cmd = rr
oldcert = $insta::certout # insta.cert.pem
[ssl_sect]
system_default = system_default_sect
system_default = hestia_openssl_sect
[hestia_openssl_sect]
Ciphersuites = TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384
Options = PrioritizeChaCha
system_default = hestia_openssl_sect
[hestia_openssl_sect]
Ciphersuites = TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384
Options = PrioritizeChaCha
[system_default_sect]
CipherString = DEFAULT:@SECLEVEL=2

[hestia_openssl_sect] is duplicated.

The last part should look like this:

# Certificate revocation
cmd = rr
oldcert = $insta::certout # insta.cert.pem

[ssl_sect]
system_default = system_default_sect
system_default = hestia_openssl_sect

[hestia_openssl_sect]
Ciphersuites = TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384
Options = PrioritizeChaCha

[system_default_sect]
CipherString = DEFAULT:@SECLEVEL=2

Or if you want the entire file:

#
# OpenSSL example configuration file.
# See doc/man5/config.pod for more info.
#
# This is mostly being used for generation of certificate requests,
# but may be used for auto loading of providers

# Note that you can include other files from the main configuration
# file using the .include directive.
#.include filename

# This definition stops the following lines choking if HOME isn't
# defined.
HOME                    = .

 # Use this in order to automatically load providers.
openssl_conf = openssl_init

# Comment out the next line to ignore configuration errors
config_diagnostics = 1

# Extra OBJECT IDENTIFIER info:
# oid_file       = $ENV::HOME/.oid
oid_section = new_oids

# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions            =
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)

[ new_oids ]
# We can add new OIDs in here for use by 'ca', 'req' and 'ts'.
# Add a simple OID like this:
# testoid1=1.2.3.4
# Or use config file substitution like this:
# testoid2=${testoid1}.5.6

# Policies used by the TSA examples.
tsa_policy1 = 1.2.3.4.1
tsa_policy2 = 1.2.3.4.5.6
tsa_policy3 = 1.2.3.4.5.7

# For FIPS
# Optionally include a file that is generated by the OpenSSL fipsinstall
# application. This file contains configuration data required by the OpenSSL
# fips provider. It contains a named section e.g. [fips_sect] which is
# referenced from the [provider_sect] below.
# Refer to the OpenSSL security policy for more information.
# .include fipsmodule.cnf

[openssl_init]
providers = provider_sect
ssl_conf = ssl_sect

# List of providers to load
[provider_sect]
default = default_sect
# The fips section name should match the section name inside the
# included fipsmodule.cnf.
# fips = fips_sect

# If no providers are activated explicitly, the default one is activated implicitly.
# See man 7 OSSL_PROVIDER-default for more details.
#
# If you add a section explicitly activating any other provider(s), you most
# probably need to explicitly activate the default provider, otherwise it
# becomes unavailable in openssl.  As a consequence applications depending on
# OpenSSL may not work correctly which could lead to significant system
# problems including inability to remotely access the system.
[default_sect]
# activate = 1


####################################################################
[ ca ]
default_ca      = CA_default            # The default ca section

####################################################################
[ CA_default ]

dir             = ./demoCA              # Where everything is kept
certs           = $dir/certs            # Where the issued certs are kept
crl_dir         = $dir/crl              # Where the issued crl are kept
database        = $dir/index.txt        # database index file.
#unique_subject = no                    # Set to 'no' to allow creation of
                                        # several certs with same subject.
new_certs_dir   = $dir/newcerts         # default place for new certs.

certificate     = $dir/cacert.pem       # The CA certificate
serial          = $dir/serial           # The current serial number
crlnumber       = $dir/crlnumber        # the current crl number
                                        # must be commented out to leave a V1 CRL
crl             = $dir/crl.pem          # The current CRL
private_key     = $dir/private/cakey.pem# The private key

x509_extensions = usr_cert              # The extensions to add to the cert

# Comment out the following two lines for the "traditional"
# (and highly broken) format.
name_opt        = ca_default            # Subject Name options
cert_opt        = ca_default            # Certificate field options

# Extension copying option: use with caution.
# copy_extensions = copy

# Extensions to add to a CRL. Note: Netscape communicator chokes on V2 CRLs
# so this is commented out by default to leave a V1 CRL.
# crlnumber must also be commented out to leave a V1 CRL.
# crl_extensions        = crl_ext

default_days    = 365                   # how long to certify for
default_crl_days= 30                    # how long before next CRL
default_md      = default               # use public key default MD
preserve        = no                    # keep passed DN ordering

# A few difference way of specifying how similar the request should look
# For type CA, the listed attributes must be the same, and the optional
# and supplied fields are just that :-)
policy          = policy_match

# For the CA policy
[ policy_match ]
countryName             = match
stateOrProvinceName     = match
organizationName        = match
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

# For the 'anything' policy
# At this point in time, you must list all acceptable 'object'
# types.
[ policy_anything ]
countryName             = optional
stateOrProvinceName     = optional
localityName            = optional
organizationName        = optional
organizationalUnitName  = optional
commonName              = supplied
emailAddress            = optional

####################################################################
[ req ]
default_bits            = 2048
default_keyfile         = privkey.pem
distinguished_name      = req_distinguished_name
attributes              = req_attributes
x509_extensions = v3_ca # The extensions to add to the self signed cert

# Passwords for private keys if not present they will be prompted for
# input_password = secret
# output_password = secret

# This sets a mask for permitted string types. There are several options.
# default: PrintableString, T61String, BMPString.
# pkix   : PrintableString, BMPString (PKIX recommendation before 2004)
# utf8only: only UTF8Strings (PKIX recommendation after 2004).
# nombstr : PrintableString, T61String (no BMPStrings or UTF8Strings).
# MASK:XXXX a literal mask value.
# WARNING: ancient versions of Netscape crash on BMPStrings or UTF8Strings.
string_mask = utf8only

# req_extensions = v3_req # The extensions to add to a certificate request

[ req_distinguished_name ]
countryName                     = Country Name (2 letter code)
countryName_default             = AU
countryName_min                 = 2
countryName_max                 = 2

stateOrProvinceName             = State or Province Name (full name)
stateOrProvinceName_default     = Some-State

localityName                    = Locality Name (eg, city)

0.organizationName              = Organization Name (eg, company)
0.organizationName_default      = Internet Widgits Pty Ltd

# we can do this but it is not needed normally :-)
#1.organizationName             = Second Organization Name (eg, company)
#1.organizationName_default     = World Wide Web Pty Ltd

organizationalUnitName          = Organizational Unit Name (eg, section)
#organizationalUnitName_default =

commonName                      = Common Name (e.g. server FQDN or YOUR name)
commonName_max                  = 64

emailAddress                    = Email Address
emailAddress_max                = 64

# SET-ex3                       = SET extension number 3

[ req_attributes ]
challengePassword               = A challenge password
challengePassword_min           = 4
challengePassword_max           = 20

unstructuredName                = An optional company name

[ usr_cert ]

# These extensions are added when 'ca' signs a request.

# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer

# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# An alternative to produce certificates that aren't
# deprecated according to PKIX.
# subjectAltName=email:move

# Copy subject details
# issuerAltName=issuer:copy

# This is required for TSA certificates.
# extendedKeyUsage = critical,timeStamping

[ v3_req ]

# Extensions to add to a certificate request

basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment

[ v3_ca ]


# Extensions for a typical CA


# PKIX recommendation.

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid:always,issuer

basicConstraints = critical,CA:true

# Key usage: this is typical for a CA certificate. However since it will
# prevent it being used as an test self-signed certificate it is best
# left out by default.
# keyUsage = cRLSign, keyCertSign

# Include email address in subject alt name: another PKIX recommendation
# subjectAltName=email:copy
# Copy issuer details
# issuerAltName=issuer:copy

# DER hex encoding of an extension: beware experts only!
# obj=DER:02:03
# Where 'obj' is a standard or added object
# You can even override a supported extension:
# basicConstraints= critical, DER:30:03:01:01:FF

[ crl_ext ]

# CRL extensions.
# Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.

# issuerAltName=issuer:copy
authorityKeyIdentifier=keyid:always

[ proxy_cert_ext ]
# These extensions should be added when creating a proxy certificate

# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer

# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# An alternative to produce certificates that aren't
# deprecated according to PKIX.
# subjectAltName=email:move

# Copy subject details
# issuerAltName=issuer:copy

# This really needs to be in place for it to be a proxy certificate.
proxyCertInfo=critical,language:id-ppl-anyLanguage,pathlen:3,policy:foo

####################################################################
[ tsa ]

default_tsa = tsa_config1       # the default TSA section

[ tsa_config1 ]

# These are used by the TSA reply generation only.
dir             = ./demoCA              # TSA root directory
serial          = $dir/tsaserial        # The current serial number (mandatory)
crypto_device   = builtin               # OpenSSL engine to use for signing
signer_cert     = $dir/tsacert.pem      # The TSA signing certificate
                                        # (optional)
certs           = $dir/cacert.pem       # Certificate chain to include in reply
                                        # (optional)
signer_key      = $dir/private/tsakey.pem # The TSA private key (optional)
signer_digest  = sha256                 # Signing digest to use. (Optional)
default_policy  = tsa_policy1           # Policy if request did not specify it
                                        # (optional)
other_policies  = tsa_policy2, tsa_policy3      # acceptable policies (optional)
digests     = sha1, sha256, sha384, sha512  # Acceptable message digests (mandatory)
accuracy        = secs:1, millisecs:500, microsecs:100  # (optional)
clock_precision_digits  = 0     # number of digits after dot. (optional)
ordering                = yes   # Is ordering defined for timestamps?
                                # (optional, default: no)
tsa_name                = yes   # Must the TSA name be included in the reply?
                                # (optional, default: no)
ess_cert_id_chain       = no    # Must the ESS cert id chain be included?
                                # (optional, default: no)
ess_cert_id_alg         = sha1  # algorithm to compute certificate
                                # identifier (optional, default: sha1)

[insta] # CMP using Insta Demo CA
# Message transfer
server = pki.certificate.fi:8700
# proxy = # set this as far as needed, e.g., http://192.168.1.1:8080
# tls_use = 0
path = pkix/

# Server authentication
recipient = "/C=FI/O=Insta Demo/CN=Insta Demo CA" # or set srvcert or issuer
ignore_keyusage = 1 # potentially needed quirk
unprotected_errors = 1 # potentially needed quirk
extracertsout = insta.extracerts.pem

# Client authentication
ref = 3078 # user identification
secret = pass:insta # can be used for both client and server side

# Generic message options
cmd = ir # default operation, can be overridden on cmd line with, e.g., kur

# Certificate enrollment
subject = "/CN=openssl-cmp-test"
newkey = insta.priv.pem
out_trusted = insta.ca.crt
certout = insta.cert.pem

[pbm] # Password-based protection for Insta CA
# Server and client authentication
ref = $insta::ref # 3078
secret = $insta::secret # pass:insta

[signature] # Signature-based protection for Insta CA
# Server authentication
trusted = insta.ca.crt # does not include keyUsage digitalSignature

# Client authentication
secret = # disable PBM
key = $insta::newkey # insta.priv.pem
cert = $insta::certout # insta.cert.pem

[ir]
cmd = ir

[cr]
cmd = cr

[kur]
# Certificate update
cmd = kur
oldcert = $insta::certout # insta.cert.pem

[rr]
# Certificate revocation
cmd = rr
oldcert = $insta::certout # insta.cert.pem

[ssl_sect]
system_default = system_default_sect
system_default = hestia_openssl_sect

[hestia_openssl_sect]
Ciphersuites = TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384
Options = PrioritizeChaCha

[system_default_sect]
CipherString = DEFAULT:@SECLEVEL=2
root@painel:~# openssl s_client -connect mail.minenge.com.br:993
CONNECTED(00000003)
write:errno=104
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 321 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---

Did you change the entire file and restarted dovecot?

Yes, I modified it and restarted.

Just for the records, we solved it modifying the 10-ssl.conf dovecot’s file.

This was the current 10-ssl.conf file:

ssl = required
ssl_cert = </home/Minenge/conf/web/minenge.com.br/ssl/minenge.com.br.pem
ssl_key = </home/Minenge/conf//web/minenge.com.br/ssl/minenge.com.br.key
ssl_dh=</etc/ssl/dh.pem
#ssl_cert = </etc/ssl/dovecot/dovecot.pem
#ssl_key = </etc/ssl/dovecot/dovecot.key
ssl_min_protocol = TLSv1.2
ssl_cipher_list = PROFILE=SYSTEM
ssl_prefer_server_ciphers = yes

And this is the modified file:

ssl = yes
ssl_cipher_list = ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-SHA256
ssl_min_protocol = TLSv1.2
ssl_prefer_server_ciphers = yes

ssl_cert = </usr/local/hestia/ssl/certificate.crt
ssl_key = </usr/local/hestia/ssl/certificate.key

# From and up to version 2.2
#ssl_dh_parameters_length = 4096

# From version 2.3
ssl_dh = </etc/ssl/dhparam.pem

Once modified and dovecot restarted, it works fine again.

3 Likes

Thank you very much!

2 Likes

Thank YOU :wink:

1 Like