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Exchange 2010 and SMTP settings

by Dave 2. March 2011 09:43

Recently I had an email exchange with a customer about sending email through MS Exchange 2010, using aspNetEmail.

aspNetEmail had been running fine when they were emailing through Exchange 2007, however, when they upgraded, everything quit working, and started throwing 2 main errors.

The 2 errors were:

a) "504 5.7.4 Unrecognized authentication type"
And, once (a) was resolved, (b) happened:
b) "550 5.7.1 Client does not have permission to send as this sender"

Lets talk about these 2 errors.

504 5.7.4 Unrecognized authentication type
In this particular instance, the customer was using the AuthLogin authentication scheme in aspNetEmail. However, starting in Exchange 2010, the only authentication mechanism enabled is NTLM. On their Exchange 2007 server, they had other authentication schemes enabled. So, as soon as they upgraded to Exchange 2010, aspNetEmail was throwing an exception, basically saying that AuthLogin was no longer supported.

There are 2 ways to resolve this.
a) In the code, tell aspNetEmail to use the NTLM authentication scheme. In this instance, the customer didn't want to touch the code base. So they decided for option (b), which was:
b) Enable AuthLogin authenticaton on Exchange. To do this:
In the Exchange console under server configuration:
   Select hub transport.
   Right click  the client server and select properties.
   Select the authentication tab.
   Check the Basic Authentication checkbox.
   Uncheck the Offer Basic only after TLS

You may have to restart the Exchange services.

Once this was resolved, the next error was thrown.

550 5.7.1 Client does not have permission to send as this sender
This error was being thrown because the FROM address the customer was using, was different than the Exchange mailbox they were relaying through. Like the error message implies, this is a permissions issue. To resolve this, the following steps were taken.
a)From an Exchange Command prompt, run the following command:
Add-AdPermission -Identity "Default Receive Connector" -User "NT AUTHORITY\Authenticated Users" -ExtendedRights ms-Exch-SMTP-Accept-Any-Sender

c) On the user account, in Active Directory, under Security, under the SELF account, select the Manage Send As Permission option.

More info can be found here:
As always, if you are modifying settings on Exchange, talk these changes over with your Exchange admin.

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