Mail on Sierra: Can't send or save outgoing server settings

Question

Mail on Sierra: Can't send or save outgoing server settings

Outgoing Mail not working

Hi, I use a desktop Mac running Sierra. Mail suddenly stopped sending mail on Saturday evening. I tried re-entering server settings in Preferences/SMTP Server List, and send a couple of test messages, but Mail refuses to save the SMTP settings. It claims that there either isn't an outgoing server, or Server Offline, and won't store what I type in.

I've been in touch with my ISP and they tested my username and password, and said those are fine.

Please advise.

MacBook Pro 13″

Posted on Dec 10, 2025 1:55 PM

Reply

Answer 1

Top-ranking reply

azaksalmarzur28

Level 4

1,098 points

Dec 10, 2025 10:51 PM in response to Silverwhistle

Turn OFF SSL in the SMTP settings

This often works if your ISP still allows port 587 with STARTTLS fallback or unencrypted port 25.

Steps:

Mail → Preferences → Accounts → Outgoing Mail Server (SMTP) → Edit SMTP Server List →

Advanced tab:

Uncheck “Use SSL”
Set port to 587
Authentication: Password
Enter your username & password again
Save

Try sending again.

If it saves successfully, Sierra was failing the SSL handshake.

Reply

Answer 2

Dec 11, 2025 12:10 PM in response to azaksalmarzur28

Hi, Thanks. I've tried this, but it's refusing to Save.

Reply