Mail Not Responding after Sequoia 15.4 upgrade

I have the same issue. When starting the mail, it will crush immediately.

On another computer I have still 15.3. There, the email first crushed, too, but after restart it works. Seems to have something to do with 15.4.

This needs an urgent fix!!!

POSSIBLE WORK-AROUND FIX - If you are able to open Mail and compose, but the send button grays out when you hit it - it looks like this is a spell-check issue. I hit send, the button grays out, I then go to "Edit / Spelling and Grammar" and click "Check Document Now", then it sends. Hope this helps some people.

Had same problem. After upgrading to Sequoia 15.4, Mac Mail "Send" button on email message grayed out and email would not send. Changed "Check Spelling" to "Never." Emails now seem to be sending properly. Thank you fletcher135.

Kind of hard to believe they'd let Sequoia 15.4 out the door with none of the alpha testers catching the fact that Apple Mail's spell-check kills the ability to SEND. I only used spell-check for one reason - gives me one last chance to make sure a) i'm emailing the right person, b) i'm saying what i meant to say, c) if there's a more economical way to say it, etc. Helpful - but Apple came up with the ultimate check on whether the email is correctly addressed and written — just not be able to send it at all.

Wow! Big thanks for this ヽ(ヅ)ノ. I was going crazy since last night getting Mail to send on the Macbook Pro: Deleted preferences; started in Safe Mode; tested iCloud web & IPhone mail (both worked); toggled Mail on & off in Internet Accounts in System Settings... Truly appreciate I found this answer, man ٩(◕‿◕｡)۶

Did you lose all the emails that you had in folders when you deleted your email account? I would like to try delete my Mac Mail and then add it back, but don't want to delete my email folders.

Both 6 days before and now after my up grade to Sequoia 15.5, I can't send emails. They appear to send, but no one receives them, including myself. I can receive emails.

Yup, Mail won't launch. Hangs and has to be force quit. Repaired permissions, used a utility to optimize Mail, re-installed the OS, Mail still won't launch, hangs and has to be force quit.

Not good.

I have the same issue.

Same - Mail will launch and receive but cannot send.

I am getting an Application not responding.

I found a way to launch the app but it involves making pop emails inactive

Me, too! Highly aggravating. I deleted the mail indexes and tried to have the message reload from the server, but but the process stopped at the very end telling me an error had occurred.

Thanks, worked for me. Now I'm receiving and able to send mail. But, number count of unread emails isn't correct (but that's minor compared to not getting or being able to send.)