IMAP breaking (remote connection)

[Wicked]

Hello,

I`ve been using Hestia on a VPS for web+incoming mail. But due to DDoS attacks I´ve decided to keep my website on a separate server. After moving my website I´m getting this error pretty often:

Can not authenticate to IMAP server: [UNAVAILABLE] Maximum number of connections from user+IP exceeded (mail_max_user

- [CLOSED] IMAP connection broken (server response)

I´m guessing the reason is because I now connect remotely. But is there a way to disable this check or make the maximum number “unlimited”? I receive large amounts of incoming emails from my website and there is lots of connection from one specific IP.

I have tried looking into the following topics without success:

Raise IMAP connections limit per IP

Hello! My customers are complaining about a message in Thunderbird saying that it is not possible to connect to the IMAP server because the limit of connections per IP has been reached. I have been struggling with this for some time now and I have tried: /etc/dovecot/conf.d/20-imap.conf And set: mail_max_userip_connections = 200 Still having the same issue. Any ideas? From the client side, we have also limited the connections per client to 1.

Fail2ban dovecot-whitelist

I have been thinking about clients being banned out of the mail server because of a misconfigured device in a small office of 10 users. The idea is to add to ignoreip the successful login IPs so they don’t get banned in 14400 seconds. I successfully implemented the solution. I hope this helps. I have followed this manual: Using a Fail2Ban Jail to Whitelist a User < System | The Art of Web Edit /etc/fail2ban/jail.local and add: [dovecot-whitelist] enabled = true filter = dovecot-whitel…

Maybe you have any suggestions, @jlguerrero

[jlguerrero]

For the dovecot whitelist you may use your servers IP in the global fail2ban whitelist. But you are not having problems with this.

As for the limits, you have to raise them to fit your needs. I can’t give you a better advice.

The only thing that you can try is an external SMTP but you will also have to increase the limits.

[Wicked]

Thanks for your reply.

Weirdly I raised the limit before going to bed, and still they seems to be reached.

Dec 31 02:36:14 imap-login: Info: Maximum number of connections from user+IP exceeded (mail_max_userip_connections=1000): user=<[email protected]>, method=PLAIN, rip=X.X.X.X, lip=X.X.X.X, se>

Dec 31 02:36:15 master: Warning: service(stats): client_limit (1000) reached, client connections are being dropped

[eris]

Check if your server closes the connection to the mail server