Problems sending e-mails

I have a customer with an invoicing program at Windows XP.

It connects via SMTP to send invoices, until a few weeks ago it connected via a PLESK to do so, since we switched to HestiaCP they can’t send invoices with the system.

In theory the program connects with or are SSL, but it does not support any of the ports and does not allow to use TSL.

Any ideas on how to solve this problem?

Oh my god!

What was the conf of Plesk, I mean which protocols were allowed (SSL 3.0, TLS 1.0…) which port uses that invoice program to connect to your mail server?

It doesn’t support TLS or doesn’t support STARTTLS?


1.- Destroy that Windows XP, your customer should switck to a supported OS and a modern invoice system that allows the use of modern TLS protocols and ciphersuites.

2.- If the ip is always the same, edit /etc/exim4/exim4.conf.template and add the ip to the directive auth_advertise_hosts

Something like this:

auth_advertise_hosts = : localhost : ${if eq{$tls_in_cipher}{}{}{*}}

Save the file and restart exim:

systemctl restart exim4

Now configure that invoice system to send the mails without SSL/TLS via port 25.

3.- Add support to whatever that invoice program and windows xp supports, as far as I know it at least support TLS 1.0 but I think there was some options to add support to TLS 1.1 and TLS 1.2. Regarding downgrading security, I can’t recommend this.