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We have an Exchange 2016 and we have this issue:

  • on some of our customers servers we must configure some email alerts that are sent through a SMTP connector (with STARTTLS and AUTH-LOGIN enabled)

  • the destination address is To: people@customerdomain.com

  • the SMTP user is alert@ourcompany.com

  • if we specify From: alert@ourcompany.it then everything is fine

  • but if we specify From: alertservice@customerdomain.com our server reports this error

:

 [S] 235 2.7.0 Authentication successful
 ....
 550 5.7.60 SMTP; Client does not have permissions to send as this sender

The error occurs both if we use a FrontendTransport receive connector or a HubTransport receive connector.

We searched for a solution but we didn't find anything.

Is there a setting that allows to use any From: address when relaying mail for authenticated SMTP users?

Thanks.

Edigest2
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1 Answers1

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If the server is the mail server for all these domains, it's possible for example to add all these addresses as proxyAddresses in AD, e.g. smtp:alertservice@example.com. If the address already belongs to another account, the account should have a send on behalf / send as permission for that address.

If your server is not a mail server for these domains, please consider that it may not be listed as a permitted sender in SPF, causing these messages to be rejected or treated as spam. Therefore, it may be a better idea to use an email address of your own domain; the one that didn't have this problem in the first place.

Esa Jokinen
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