Ever since changing to Thunderbird as the email client, I've had almost zero problems with it until recently in the past few months.
However, when it does have issues, support is knowledge base articles and community volunteer based (with moderation) and that is pretty much it. When the problem is beyond the standard how-to's and the built-in tools in Thunderbird, you're pretty much stuck.
This was the issue I faced a few times this year. IMAP connection related issues, automatic filtering issues, etc. Issues that were obviously beyond the technical expertise of our volunteer troubleshooters.
Its time Thunderbird invested some of its budget to put together a proper technical support structure to deal with issues that may require developer interaction.
I doubt involving the developers will be of any use to most folk, other than to usage their feeling they have a right to tell them something. I have access to them. It gets me nowhere, except chastised for not being "nice" and "polite". If you want direct access, file a bug. But don't expect any quick actions there. There are bugs there that a 20 years old. Others get quite quick resolution. But bugs expressing dissatisfaction tend to either be ignored or closed.
What is your problem, exactly?
Advanced IMAP Settings ?
Maximum number of server connections to cache: Most servers support multiple connections. If you have an issue with connections to the server being dropped, try lowering this number.
https://wiki.mozilla.org/MailNews:Logging ? can it help you
Thunderbird Module Names, Filters, can it help you?
Illustration and for my part Windows
"C:\Program Files\Mozilla Thunderbird\thunderbird.exe"
Save your file
Type : All files
Then, click on illustration.bat, it will launch Thunderbird
.bat will open a command prompt window, this is normal
Shutting down Thunderbird will stop .bat and close the command prompt window.
And keep an eye on log_file.moz_log from time to time, in real time, because, as we've seen
Stopping Thunderbird will stop .bat, close the command prompt window and empty log_file.moz_log