Hallo all 
We got this failure very often on eM Client in our office, have some other tried get same failure? If yes please help, how to solved it, as it is almost not possible to work, because the window is popping up all the time…
Mail max userin connections=25
That is normally mail server or mail server network connection issues with not handling the amount of connections or traffic to the mail server.
Have you spoken to your server technical support about that problem ?