Mail_max_userip_connections

Hello!

Today for the first time clients got “Maximum number of connections from user+IP exceeded” (mail_max_userip_connections=20). I was setting the number higher till I reached 50. So far so good, but is there any way to check why this happens? I’ve been using mailinabox for over a year and this is the first time I see this error.

The problem is connected with one shared mailbox with 5 people in the office.

Thanks,
Adam