Use of third party email client and app-specific passwords
I have for a long time been using Thunderbird as an email client with three different providers - Apple, Gmail and TalkTalk. Until recently all these worked fine, picking up incoming emails from the different companies and sending emails via the same without hitches.
I changed my Apple ID password 3 months ago and I have not received a single email via my @me.com account depite all efforts to find what settings are wrong . This problem appears only on my iMac; my MacBook Pro and iPad all work ok.
What could be the problem? The iMac is old (mid-2011) and updated as far as it can go (High Sierra). Do I have to use a app-specific password for Thunderbird? Would changing to @Cloud.com fix it? And how do I do that?
iMac 27″, macOS 10.13