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Exchange Online Mail Enabled Users redirecting to eternal SMTP

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Ian_Culliver
New Contributor

Hi all,

I have a client that has been using Ex2010 and has used mail contacts object to effectively build a reverse DL. They have say 30 Unique contacts with a proxy address inside their Org, but use the External Email Address field to send to the same SMTP.

For example, a user contact called Bill Smith with an internal address of bill@internal.comany.com but the external address of service@companya.com

They then have Jane Doe with an internal address of jane@internal.comany.com but the external address of service@companya.com

 

So essentially the GAL allows staff to find Bill or Jane and send to them but it goes to a single external mailbox.

 

Exchange Online will not allow this bad behaviour for obvious reasons but I notice there is an Attribute in MailEnabled Users for "ForwardingAddress" that I can't use or write to. Does anybody know if ;

a) Can I write an external address to this attribute to replace the above behaviour or

b) a way to accomplish the same?

 

I know I can write a transport rule that redirects from contact Jane Doe with an internal address of jane@internal.comany.com to a Contact object of service@companya.com but this is not only messy for the number involved, but will it not also potentially cause issues with SPAM detection engines?

 

If there are any ideas, I would love to hear them.

Thanks

2 Replies
Solution

Exchange Online does not enforce uniqueness of the ExternalEmailAddress property, so you should have no trouble doing this:

 

[10:23:47]# Get-MailUser MU* | ft Name,Primary*,Externa*
Name PrimarySmtpAddress           ExternalEmailAddress
---- ------------------           --------------------
MU1  MU1@michev.info              SMTP:external@domain.com
MU2  MU2@michev.info              SMTP:external@domain.com
 
Just make sure you create them with different PrimarySMTPaddresses (use the relevant parameter for new-mailuser).

@Vasil Michev Thanks you so much Vasil, This works perfectly well as long as you stay away from the GUI and force the PrimarySMTP as you said. I was missing that step.

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