My dad had the opposite problem with his Sympatico account at the same time you wrote this (couldn't check his mail, webmail worked fine but was unsuitable for long term use). I tried everything I could think of for days but couldn't solve it. I told him to call Bell to get that out of the way so we could then talk to a person who actually knew more technical info and could look into it. After the call got him predictably nowhere ("your settings are all fine!), I told him to write Bell (https://support.bell.ca/Resolve-a-concern) and late at night a day later (like almost 11 pm our time) a tech called and gave him new EVERYTHING except email address, all the settings had changed (even the "username") and were different from what is listed as correct online. I highly recommend following this route, as annoying as it is. They never explained what caused it, but my dad has had this account for decades and I'm assuming they made a big boo boo when they moved some older accounts off an old server or something. Good luck!