Roundcube - Maximum number of connections from user+IP exceeded

[gate2vn]

I have a specific user who is sometimes blocked because of this log


[14-Oct-2025 14:26:39 +0700]: <vgq9ibg6> IMAP Error: Login failed for lisa@domain against localhost from 192.87.x.x. AUTHENTICATE PLAIN: Maximum number of connections from user+IP exceeded (mail_max_userip_connections=15) in /var/www/html/roundcubemail-1.6.11-Edk6/program/lib/Roundcube/rcube_imap.php on line 211 (GET /roundcube/?_task=mail&_caps=pdf%3D1%2Cflash%3D0%2Ctiff%3D0%2Cwebp%3D1%2Cpgpmime%3D0&_uid=46398&_mbox=INBOX&_framed=1&_action=preview)

It's not always happening. The customer answered that they only use one computer at this location, and after logging in, they are just working normally. While I can increase the mail_max_userip_connections, I wonder what the reason should be?

Thanks.

 

[romans]

I have a specific user who is sometimes blocked because of this log


[14-Oct-2025 14:26:39 +0700]: <vgq9ibg6> IMAP Error: Login failed for lisa@domain against localhost from 192.87.x.x. AUTHENTICATE PLAIN: Maximum number of connections from user+IP exceeded (mail_max_userip_connections=15) in /var/www/html/roundcubemail-1.6.11-Edk6/program/lib/Roundcube/rcube_imap.php on line 211 (GET /roundcube/?_task=mail&_caps=pdf%3D1%2Cflash%3D0%2Ctiff%3D0%2Cwebp%3D1%2Cpgpmime%3D0&_uid=46398&_mbox=INBOX&_framed=1&_action=preview)

It's not always happening. The customer answered that they only use one computer at this location, and after logging in, they are just working normally. While I can increase the mail_max_userip_connections, I wonder what the reason should be?

Thanks.

You can check this forum article with the similar request:

https://forum.directadmin.com/threads/max-imap-connection-limits-per-ip-and-increasing.73194/

Hope it will solve your problem too.

 

[gate2vn]

Like I wrote, I can increase that value, I want to know what the reason is. The problem is happening randomly, and for some users only, not all.

 

[Ohm J]

Yep, I got the logs by using multiple browser tab, but I have the self unblock for my customer, I just leave it like this.