I'm not getting the same behavior (sometimes hangs on sending email) on another computer (MacOSX High Sierra 10.13.6).

I'm now experiencing the same issue with 60.5.0.

I installed version 52.9.1 (64-bit) on my MacOSX machine, and the problem goes away. I did not even have to wipe out my profile directory.

On Windows 10, with Thunderbird 60.5.0 32-bit, I do not have the problem. I access the same imap and gmail accounts on both Windows and MacOSX.

Still having the same issue with 60.5.1. I wonder if anyone reads these threads.

With 52.9.1, I do not encounter the problem. My daily routine: Give it a try with 60.x until it hangs, then revert to 52.9.1 for the rest of the day.

On whichever computers with TB 60 installed that have the problem, start the computer (Windows or OS X) in safe mode and see if the problem remains when you run TB.

https://support.microsoft.com/en-ca/help/12376/windows-10-start-your-pc-in-safe-mode

https://support.apple.com/en-ca/HT201262

sfhowes said

On whichever computers with TB 60 installed that have the problem, start the computer (Windows or OS X) in safe mode and see if the problem remains when you run TB. https://support.microsoft.com/en-ca/help/12376/windows-10-start-your-pc-in-safe-mode https://support.apple.com/en-ca/HT201262

Thanks for the reply. I followed the instructions and restarted my Mac in "safe mode" following the instructions found on the page you posted. I then started Thunderbird, also in safe mode (add ons disabled). After working with it for a while, it hanged the same way while sending an email. I left it there for more than 5 minutes, and it is still unresponding. Every time it hangs, the email is sent correctly, but Thunderbird does not respond anymore and I have to "force quit" to end it.

I'm still getting the same behavior (freezes once in a while after sending an email) with TB 60.5.2.

I can't explain why TB on the Mac is freezing, so I suggest you downgrade to TB 52 in the meantime.

I'm still getting the same behavior (freezes once in a while after sending an email) with TB 60.5.3.

Could be so many things and I don't use Macs but I have performance issues when memory is low, my inbox is very large, or when the anti-virus scans the profile folder.

I have 32 Gb of RAM and no anti-virus, plus I still had the issue with both the Mac and Thunderbird running in "safe mode". Furthermore, no other apps are freezing as frequently as Thunderbird (Thunderbird 60 freezes multiple times a day while other apps freeze once in a few weeks). So, I see your point, but the problem never happens with Thunderbird 52 and regularly happens with Thunderbird 60. I upgraded to 60.6.0 and I'm still getting the problem.

I do have large folders (up to 2.5 Gb). I'll try to bring these down to see if it helps in any way. My inbox folders, on the other hand, are in the range of 500 Mb.

Upgraded to 60.6.1 and brought down my largest folder to below 2.3 Gb and below 17k messages, but I'm still experiencing the same issue.

You can go through this list and see if any of them apply. Some items refer to Windows-only setups. Windows or global search indexing are common sources of poor performance.

My imap folders are now below 2.0 Gb and below 15k messages. My largest local folder is 3.4 Gb. Things I changed with respect to the list posted by sfhowes: Mac Spotlight Integration: disabled Gmail All Mail folder: unsubscribed Global Search and Indexer: disabled With all of the above, I'm still experiencing TB sometimes hanging right after I send a message. I'll continue to change my configuration given the list posted by sfhowes with the hope that it will eventually resolve the issue.

One thing to confirm with gmail accounts is that you don't have 'Place a copy in' enabled in Copies & Folders for the account in Tools/Account Settings, as gmail automatically copies sent messages.

https://support.mozilla.org/en-US/questions/1254264

That, plus disabling antivirus scanning of outgoing mail.

Gmail smtp settings: smtp.gmail.com on port 587, STARTTLS security, OAuth authentication, User name = email address.

Thanks again sfhowes for the links to potential sources of problems and solutions.

My latest progress with the problem: - Imap folders are below 2.0 Gb and below 15k messages. - Largest local folder is 3.0 Gb. - panacea.dat is 608 KB (so much below 10 MB)

Things I changed with the hope of resolving the problem: - Mac Spotlight Integration: disabled - Gmail All Mail folder: unsubscribed - Global Search and Indexer: disabled - "Place a copy in" for gmail accounts: disabled - Gmail smtp set to port 587, STARTTLS security, OAuth authentication, User name = email address

With all of the above, I'm still experiencing TB regularly (multiple times a day) hanging right after I send a message.

When TB is frozen: - CPU consumption = 0.2% - memory consumption = 868 MB and holding steady - total disk use was 429 MB written and 374 MB read and holding steady

I'll continue to change my configuration given the list posted by sfhowes with the hope that it will eventually resolve the issue (I still have 5 things to try out).

While you are trying different things, it may be worth creating a new profile with Profile Manager, setting up one account, and seeing if a fresh profile makes any difference. You can easily start TB in the old or new profile without one affecting the other.

Further things I changed with the hope of resolving the problem: Lowered my Imap folders from 1.9 to 1.8 Gb Lowered my largest local folder to 2.0 Gb Lowered largest address book 3640 to 3630 contacts Lowered total number of contacts from 6252 to 6242

Regarding the item "Are any non-Inbox IMAP folders configured to check for new messages (via "always check this folder" in properties)? Or have hidden preference mail.check_all_imap_folders_for_new set to true? " from the "https://wiki.mozilla.org/Thunderbird:Testing:Memory_Usage_Problems" list, I could not find such an entry in the settings (Preferences, Advanced, Config Editor). I have mail.server.default.check_all_folders_for_new set to false, mail.server.default.check_time set to 10, and mail.server.server1.check_new_mail set to true (same for server3 and server 4).

With all of the above, I'm still experiencing the problem.

Further things I changed with the hope of resolving the problem: Lowered my Imap folders from 1.8 to 1.6 Gb Lowered my largest local from 2.0 to 1.8 Gb Lowered largest address book 3630 to 3619 contacts Lowered total number of contacts from 6242 to 6231 Lowered the largest number of emails in an Imag folder from 15k to 13k

Disabled "Auto Save every" (Preferences, Composition, General, Auto Save every) Changed checks for new mail from every 10 minutes to every 15 minutes.

With all of the above, Thunderbird still froze and I had to "Force quit" to kill the process.

As before, I recommend creating a new profile and setting up an account. If the new profile works without issues, it indicates the settings and overall computing environment, e.g. antivirus etc., are satisfactory, and some of the mail folders in the original profile are defective. I don't think the size of you mail folders or address books is cause for concern, for even a modest hardware setup.