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Recieving error: 550 This is a submission only port. You must authenticate before sending mail
Problem reported by Nikhil Katara - 1/22/2019 at 12:55 AM
Submitted
Hello Team,

This is to inform you that we are experiencing the below issue while receiving the emails from third party domain users.

Error: smtp; 550 This is a submission only port. You must authenticate before sending mail

For complete error message we are attaching the file.

Can you help me to understand why i am getting this error while receiving the email from the domains. Also where can i check these settings in SMARTERMAIL

We are using  :SmarterMail Professional Edition - Version: 16.3.6897

Regards.
Anil P

2 Replies

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0
Masood Naaj Replied
9/23/2023 at 7:40 AM
Hello,

I also had the same problem, to this i have change the port type from Submission to SMTP (587) after that issue resolve.



Regards,
Masood NA
0
Douglas Foster Replied
9/23/2023 at 6:56 PM
Recommended settings:
Port 25 should be configured as "SMTP TLS" (which means StartTLS and encryption optional)
Port 587 should be configured as "SMTP Submission Port SSL" (which means encryption required)

If this is how you are configured, then someone is attacking port 587, and you want them to be blocked.

If you configured port 25 as "SMTP Submission Port", you should switch it back.
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