Sorry, there is a third problem. The window displaying TB just starts moving itself around the screen. It just won't stay put where I put it. I might use Moom to have it on the left two thirds of my right monitor and then it moves randomly. Then I disabled Moom and used a window manager from Parallels tools and then it changes monitors randomly and appears on the other monitor. No other program does this or reacts to these window managers this way. This program is highly defective and a big disapointment.

I now have two issues, one is that on my IMAP accounts with my own domain, both the recent sent and recent received emails in a thread are showing up twice. This doesn't happen with previous emails in that thread or with gmail, exchange, outlook.com, live.com, icloud, etc....

That has been a known issue with Microsoft's various mail domain offerings as well as gmail. Both force a copy of sent mail as it goes out through their servers. The simple solution is to turn off Thunderbird's saving a copy in account settings.

Now, I have an issue where the pop ups for calendar notifications keep popping up non stop and either won't go away by hitting "Submit to changes anyway" or if they do go away, they immediately pop back up again. 115 is a big disapointment for me, it's been highly glitchy, many add ons no longer, some that should work, don't work properly, it was hyped a major upgrade and I see very little that distinguishes if from 102 in any meaningful way except some of the icons are more colorful. Is there a way to go back to 102? Either that or I may start using Mac Mail again due to all these bugs.

This bit I can't offer much on. Perhaps use the feedback forum linked from the help menu and let the developers know what you feel. This is what the team are thinking at the moment. https://thunderbird.topicbox.com/groups/planning/T1811fa406e939644/a-good-email-client-thats-good-for-you

Sorry, there is a third problem. The window displaying TB just starts moving itself around the screen. It just won't stay put where I put it. I might use Moom to have it on the left two thirds of my right monitor and then it moves randomly. Then I disabled Moom and used a window manager from Parallels tools and then it changes monitors randomly and appears on the other monitor. No other program does this or reacts to these window managers this way. This program is highly defective and a big disapointment.

Hi chunnel. Support is more effective for everyone when you "Create one thread and only one thread for each subject", even if you are posting in your own thread. https://support.mozilla.org/en-US/kb/mozilla-support-rules-guidelines#w_posting-support-requests. Please in the future have a separate thread and title for each issue.

pop ups for calendar notifications keep popping up non stop and either won't go away by hitting "Submit to changes anyway" or if they do go away, they immediately pop back up again.

I believe you are referring to reminders? This is a known issue, which unfortunately may take a long time to resolve (at least, so far it has).

Thank you for the response, but the problem for me has resolved itself. I have not seen this since a week or so after posting.