Error "… Select an outgoing mail server from the list below," every time I try to send emails with my iCloud account on MacBook Air

It is suggested reading the Apple Support Document that my bring some Important information on this issue

refer below

iCloud Mail server settings for other email client apps

Excerpt from above link

SMTP information for the outgoing iCloud Mail server

• Server name: smtp.mail.me.com
• SSL Required: Yes
  • If you see an error message when using SSL, try using TLS or STARTTLS instead.
• Port: 587
• SMTP Authentication Required: Yes
• Username: Your full iCloud Mail email address (for example, johnappleseed@icloud.com, not johnappleseed)

I had a very long discussion with Apple support yesterday. The support person said that there is a known problem with the iCloud SMTP (outgoing mail) server when using a mac.com email address with Mail on some Mac computers. I have an M1 MBA.

A temporary fix is to turn iCloud mail OFF, restart the machine, turn iCloud mail back ON. The fix may last a day or a week. Totally unpredictable.

The are researching the issue. I will post here if I learn anything more.

Same here. Never had any difficulty until the last few weeks. And, it's only on my M1 MBA; doesn't affect outgoing mail on any other device. My not-very-brilliant guess is that it has something to do with how Apple has implemented TLS for some Apple Silicon machines.

Thank you for your observations and do appreciate them.

Keep up the good work too.

Did have a short lived issue in Sonoma and Mail

Mail was taking itself Off Line for not apparent reason

Issue was occurring for maybe 4 - 5 days

Was Elevated to Level 2 Apple Engineering

Within about 24 to 36 hours the issue was resolved and continues as a Non Issue here

No updates required

Still on Sonoma 14.0

👍

Interesting as My xx@mac.com e-mail account has been working fine since day one