Emails have stopped working since upgrading to v8.+

[slugshead]

I finally bit the bullet and upgraded to version 8.1.16 where I had to upgrade php too, from version 6.something. I've upgraded php to v8.2.28. Upgraded through the oneliner.

But I've found that emails are simply not working.

First things I tried were php artisan config:clear and php artisan config:cache

I've not got any errors in laravel.log, debug is set to true and there's nothing referencing the emails.

I've updated the .env to remove MAIL_ENCRYPTION=null and add MAIL_TLS_VERIFY_PEER=true. No change.

I'm using internal exchange servers as the smtp relays, tried setting ports 25 and 587 in the .env.

I can confirm that the IP address is allowed to send anonymous emails (Whitelisted the servers subnet).

There's nothing in the php error log that refers to smtp errors.

There's nothing in the SMTP logs on the exchange servers.

Snipeit is hosted on IIS

Is there anything I've missed?!

[slugshead]

After sleeping on it - Changed MAIL_TLS_VERIFY_PEER= to false. Ran another php artisan config:clear and php artisan config:cache and my emails are now delivering...