Error sending emails: SMTP Error 550 relay access denied

[figaro76]

SYSTEM INFORMATION
OS type and version	Ubuntu Linux 22.04.5
Webmin version	2.202

I’m trying to configure the Sending Email feature, but keep getting this error while testing:

… sending failed : SMTP command rcpt to: myaddress@outlook.com failed : 550 relay access denied - please authenticate

I’m using an SMTP service (SMTP2Go) and have configured the settings accordingly (including the smtp login/pwd and auth method), besides I use this service in another systems without issues so I don’t think that is the problem.

Next to the error message there’s a question mark that reads: “mailboxes/boxes-lib.pl (line 1388)”

As the intention is to only send email for alerting purposes and not receiving, I have not configured the email servers section. Is it necesary?

When I enter the section: ''Read User Mail" it says: " None of the supported mail servers (Exim, Qmail, Postfix and Sendmail) were detected on your system. You will need to adjust the [module configuration] to set the mail server and possibly mail paths manually."

Are any of these mail servers necesary to only relay email from this system?

Edit: added requested screenshot

[stefan1959]

@figaro76

Sending Email feature

Not sure where this is, can you send a screenshot

[figaro76]

added to post

[stefan1959]

My account has 2525 as the port on smtp2go but I see you can use that port.

Maybe you haven’t added the correct username on purpose but its I usually a email address

You may need to encrypt as well.

Ok, it maybe a bug, I get the same thing. @jamie has this been tested latley
Looks like the username and password is not getting sent.

[Jamie]

Does your SMTP provider perhaps only support certain authentication types? Also, have you tried using one of the SSL ports and turning on encryption?

[stefan1959]

Yep tried all the combinations. Using ttps://www.smtp2go.com

Connecting via SMTP

SMTP Server: mail.smtp2go.com
SMTP Port: 2525
Alternative ports: 8025, 587, 80 or 25. TLS is available on the same ports.
SSL is available on ports 465, 8465 and 443.

Best I can do is the … sending failed : SMTP command rcpt to: xxxxxxx.xxxxxx@gmail.com failed : 550 relay access denied - please authenticate

I’v used with WHM no problems.

found some more
https://www.smtp2go.com/setup/

[shoulders]

long shot, are your SPF and DKIM records correct?

Your SPF record will need the SMTP2GO IP addresses, maybe not having these correct could cause the issue.

Do you need to add your server’s IPS to a whitelist at SMTP2GO?

[stefan1959]

Thats shouldn’t matter with authentication, and smtp2go makes the user add the dns records before using the service. Ive never had to add the server IP for it to work. The authenication I would of thought would be enough security. I’m just verifying figaro76 issue from original post.

[figaro76]

Sorry for the late response, yes I tried all port/ssl/tls/auth combinations with no success.

The workaround was to use Postfix as a relay:

1. Installed Postfix
2. Followed this guide to configure Postfix to use an external smtpd
3. Successful testing using mail command:

echo "this is a test." | mail -s "the subject" -a "From: serverc14@mis****.com" rob****@gmail.com

4. Went back to the Webmin Sending Options page, changed the configuration to use Postfix and tested again with success.
   
   

But yeah as stefan1959 said, it seems webmin is not authenticating on the remote mail server.

Thanks for checking the issue.