SMTP Outbound Emails show Error 500: Unkown Error

[RedPepper]

Hello,

We recently installed a docker container for EspoCRM. It looks like a solution that fits our needs.
However, when we try to enable Outbound Emails under Administration > Outbound Emails, we get Error 500: Unknown Error.

We've tested multiple domains (gmail, company, personal) and all errors are the same.
Since we want to use EspoCRM for our company I'd like to focus on that solution which includes 2FA.

We've created a new account in our MS Tenant, when through 2FA setup, and created an App Key which is currently set as the password under SMTP.
We can see the server connecting to the outside world in our Firewall over the correct ports, but still Error 500: Unknown Error is shown.

This is what I gathered from the logging:

<IP of our host> - admin [20/Jan/2025:15:33:19 +0000] "POST /api/v1/Email/sendTest HTTP/1.1" 500 289 "https://espocrm.domain.topleveldomain/"; "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:134.0) Gecko/20100101 Firefox/134.0"

Please note I removed our IP-address and domain for privacy concerns.

We are running on version 8.4.2

Any tips in resolving this issue?

Thanks in advance.

[RedPepper]

Update: I managed to get this to work by using an external SMTP provider (SMTP2Go) after finding out Microsoft has/is going to depricate SMTPAUTH. I think this might cause issues for a lot of users in the near future (september 2025). Is espoCRM aware of this?

https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online

[anthony.senior]

I'm having a weird similar issue right now with SMTP setup for a Group Mailbox. Strangely enough, I configured all of the SMTP settings and did a Send Email test and it worked just fine. I spent another 2 minutes or so filling out the IMAP and Main tabs and went to do one last SMTP test before saving and it failed. I didn't change any SMTP settings at all since the first test which was successful.

[anthony.senior]

Took a look at the logs and found out the problem was in the "Main" tab, the Email Address there did not match the username in the SMTP settings tab. I was trying to use the email I want displayed for outgoing emails. I changed the Email Address in the Main tab to match the username in SMTP but made sure the reply-to address and "From Name" were as I wanted and that fixed everything.