Cannot send mails to mail server. (Mailbox unavailable. The server response was: 5.7.1 Unable to relay)

_{Tuesday, July 21, 2015 11:16 AM}

Hi,

I implimented a mail system as follows in Sql server 2008R2-:
Profile name  ‘ProfileDbMail’
Ac name  ‘AcDbMail’
Email address(outgoing): Dba@ourmailserver.com  (Not valid mail id in mail server)
Display :Databasemail from Binny
Reply email : Null
Server Name : ourmailserver.com
Port no :25
Ssl connection : Not Ticked
Annonymus Authentication enabled
I am using the above to send notifications thru an alert system in Sql server Agent
through an operator when any of the job fails and when the last job succeeeds in the
maintenace plans running at night.
My problem is that the database server is able to send mail internally that is it can
send a mail to all valid email id in our mail server. However it cannot send a mail to a
mail id of external exchange server like Yahoo.com or Gmail.com
The error shown in the logs of the databas email is as follows-:
Exception Message: Cannot send mails to mail server. (Mailbox unavailable.
The server response was: 5.7.1 Unable to relay).
What is the reason and how to overcome the problem?

Thanking you in advance

Binny Mathew

_{Tuesday, July 21, 2015 11:33 AM ✅Answered}

Hello Binny,

In our company the E-Mail Server is setup to block all SMTP mail going outside of our domain, to prevent mailware sending spam; may be it's the same in your company?

Olaf Helper

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_{Tuesday, July 21, 2015 12:46 PM}

configure your application to use an appropriate SMTP gateway, which will therefore probably require authentication .

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