After a period that Pegasus Mail was unable to send via SMTP, our support staff sent me the following message:

I noticed you use the authentication as below from you log:

13:44:10.028: >> 250-AUTH GSSAPI NTLM LOGIN

We don’t use this authentication method.

Could you use the authentication as below?

GSSAPI NTLM to Normal Password

I searched NTLM here in the PMAIL Community and found nothing that helped me. What is our org's Support Staff talking about? How can I make this change?

Thank you in advance,
Jay

I suggest asking them for the SMTP server settings and then creating an SMTP host in Pegasus Mail based on those settings. They should provide:

• Server name
• Port
• Encryption

Also important to know is whether the authentication username needs to be in the form of "username" or "username@domain".

I don't have a clue where the "GSSAPI NTLM" is coming from. I recognize NTLM as an authentication method on Windows/Microsoft Server networks but I don't understand how Pegasus Mail could be trying to use it.

https://mailtrap.io/blog/smtp-auth/

Has some interesting info.
Seems the full log should show what methods they support for connection.

As Brian Fluet said, some what user name without domain, and others want it with. Some will work either way.

Also, what exact settings are you using for SMTP under General and Security.
In old days we connected on port 25 with plain text, but now it is more complex.