It's probably tied to the other issues reported in the forum, like Webmail and My Cogeco login issues by extechnician and Email malfunctioning by Dingaan.
Be nice if their service status pages could be updated within a few days of widespread issues, maybe even within the hour... inaccessible email sounds like a pretty big deal to a lot of people and personally, I'd rather not have so many friends and family calling me on the weekend asking me what's up.
Just called Cogeco. Experiencing a higher than normal call volume due to issues with (wait for it) connecting to cogeco's email servers. Apparently they are urgently attempting to resolve the problems. Suspect that folks in the call centre are not having a good day.