I recently switched over from Tahrpup64 6.0.5 to Slacko64 6.0.3 after my file got corrupted. Both use Sylpheed 3.4.3 so I configured everything EXACTLY the same as I had used successfully in Tahrpup for a few years.
I can receive e-mail but can not send. Sylpheed completes the "authorization" block and then opens the "connecting" block but just sits there until it times out. The SMTP port is 587, I have tried a few other SMTP port numbers but the result doesn't vary. If I reload my Tahrpup disc (Frugal install) I can send e-mail without any problem, again, with EXACTLY the same configuration.
I am sure that it is an easy fix but I am a greyhair (if any) retiree with limited computer knowledge outside of "point and click".
Mike