It's happening again. And no, I'm not off my meds, but I'm beginning to wonder if perhaps I should be on some as this stuff is starting to make me feel really crazy. Anyone know their way around the .thunderbird directories well enough to point me toward the likely suspects? First, Comcast apparently configured our rented modem-router in such a way that imap.comcast.net failed in all instances of Thunderbird on different machines in our house. I eventually discovered and adopted the workaround of using imap.ge.xfinity.com (perfectly functional, but with invalid certificate problems, probably due to my lack of knowledge or comprehension or motivation or time to figure it all out.) Next, I purchased our own modem-router and soon discovered that with the new router imap.comcast.net works fine in all instances on different machines in our house. So I set 'em all back to imap.comcast.net recommended defaults. Smooth sailing until... Now, after a couple or three weeks of successful use, I discover that on my wife's machine that both instances of Thunderbird in separate user accounts accounts have stopped downloading emails with imap.comcast.net. Ubuntu MATE 18.04 kicks up little screen messages saying that it can't connect with imap.ge.xfinity.com--which, of course, it shouldn't now be trying to do because server settings in both accounts are configured for imap.comcast.net Where do these gremlins reside and from whence did they come? Is it witchcraft? I put it to the council: Should someone be burned at the stake or is it only a wee misunderstanding?