Sorry, I should have given more informations.

It is a web hosting provider that gives me also access to mails (Thunderbird on my PC has no problem with the mails in this right moment).

I have 3 accounts in the form adress1@domain.net, adress2@domain.net, adress3@domain.net, so all for the same domain.

It is not working since the 22 October 2014 so a couple of days ago.

IMAPS for the 3 accounts, so the port 993 is used.

No modifications were brought to the settings for at least 6 months and everything worked perfectly until a few days.

When this occurred I was in another country than my own and I was connected through OpenVPN to my home router with the traffic being redirected. I firstly thought that it wasn't updating the mails because of a bad connection but once back home and without the OpenVPN client active the updated didn't work either.

I can't really understand what happened and I don't really know how to debug this.