Hi

This does not sound like an issue with Firefox, but something that you will need to look at with your email provider.

Their services are different from one another, so I recommend having a read of this guide that will help point you int he right direction.

I hope this helps, but if not please come back here and we can look into a different solution for you.

Did you mean to post in the Thunderbird queue? If so, a Moderator can move this thread over there.