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 email@example.com but the external address of firstname.lastname@example.org
They then have Jane Doe with an internal address of email@example.com but the external address of firstname.lastname@example.org
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 email@example.com to a Contact object of firstname.lastname@example.org 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.