Gmail allows you to use something frequently referred to as plus addressing or sub-addressing.

Can Exchange 2007 be configured to do something like this? Or are there any 3rd party applications that add this type of functionality to Exchange?

  • Do you want to create just one "+" for spam or do you want exchange to route all mail from any known address with "+" or "-" ? Do you have anyone that can code for you in C# ? – JJ01 Oct 11 '09 at 0:17
  • I want anything addressed to the user+ to work. I am hoping to find that someone else has already developed a solution. At the moment developing something in house isn't an option. I was hoping someone else had already built something. – Zoredache Oct 11 '09 at 0:44

Afraid not. You can have email addresses with a + in, but exchange won't automatically send these to the right places, you would need to add them as an alias to their account, which kind of defeats the point of having them as throw away addresses.

  • My searching of Google does seem to agree that this isn't something that can be done by Exchange itself. But it sure seems like something that could be done by some 3rd party tool fairly easily. This article (msexchangeteam.com/archive/2006/12/04/431755.aspx) makes me thing that it is something that could be done by a SmtpReceiveAgent. – Zoredache Oct 1 '09 at 6:40

If we are talking a Plus Addressing, more specifically sub addressing. This convention is known as Sieve Mail Filtering Subaddress Extension Ref: [ RFC 5233 ]. In spirit, What the specification says is that john.doe+sdlc@mydomain.com will be sent to the inbox of john.doe@mydomain.com. However, because the address is passing an argument - the mail server can perform an action based on the existence of the arg via the Sievel Mail Filter Language. e.g: Kickoff a trouble ticket.

It should be noted that the argument can be alphanumeric. However; you do not want your argument to be longer than 6 characters inaccordance with the specification. Having said all that - this does not seem to be how the industry is using this feature. Instead this technique is more commonly used to create your own DEA account or (disposable email account). The idea being that you will already have a mail client rule set up sends all mail with the argument +site to a folder called W3 Notifications, +signup gets sent to the W3 Accounts folder and +junk -- well you can do with that what you want. As far as I know - most of the major players in the web mail space support sub addressing.


Security considerations are discussed in [RFC5228]. It is believed that this extension does not introduce any additional security concerns.

I hope this helps define the differences between an email alias and sub addressing.

  • Peace
  • 2
    The question was, can Microsoft exchange provide this functionality. – Zoredache Dec 16 '11 at 23:22

you'll have to go 3rd party but i know a spam filter service called reflexion can handle that. They call it "address-on-the-fly". it allows you to create user.amazon@foo.com and it automatically knows to forward it to user@foo.com. if you see spam coming to that address, you can axe the user.amazon@foo.com and your user@foo.com address still works the exact same.

  • Huh that seems like a bad idea as many organizations use First.Last@example.com as there full email. Routing mail like that would cause issues for any of them. Sub-addressing using the plus or hyphen sign is part of RFC 5233 – TrueDuality Oct 9 '09 at 14:08

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