Email Proxy (Alias) Addresses Suddenly Capped at 200?

Copper Contributor

Suddenly, aliases have been capped at 200 without any stated reason.

I have been using more than 200 aliases for 15 years because I assign a specific address to vendors to find out who sells my email address. I currently have 416 aliases. For what it's worth, I have started a support ticket but I'm wondering if anyone knows what prompted this unwelcome change?

14 Replies

Is your mailbox on an Exchange Server or Exchange Online. If Exchange Server, what version?



Office 365. Is this not the correct forum?

There's a lengthy thread about this on Answers: New limit on "proxy" addresses - unable to delete old proxy addresses or add new ones


I've pinged some MS guys on this, guess I should give them another poke.

I, too, commented on that thread with added emphasis. I'm just trying to get to the bottom of the actual reason this has suddenly been limited. It has created yet another issue I didn't need today.



The number of proxy addresses was limited because of an AD limit that can be reached otherwise.


Best regards!

I do not believe that article applies because (1) it describes the 2000 and 2003 versions of AD and (2) this change only occurred this month.


I know this because we migrated to O365 in December 2013 with accounts containing more than 300 aliases and without any such complaint. One account went over 400 earlier this year.


I log into the Exchange Admin Center almost daily and this "error" dialog only began appearing this week. There is no other conclusion I can draw except that an arbitrary, possibly accidental and certainly unwelcome policy change has occurred.


I am simply attempting to question this change as I do not believe the full impact was considered. I would like to petition for reconsideration.


Hello Jim,

The limits for non-linked multi-valued attributes are dependent on the forest functional level (FFL), but indeed, I don't think Office 365 is at the FFL from the article :). I used that article only to make it easier for me to explain what I'm talking about.

The limit of proxyAddresses was clearly not set by accident and it comes from the need to prevent any object from reaching the limits of non-linked multi-valued attributes, but I agree that it probably is unwelcomed by a few of customers.

Regarding the chances of having this limit removed, as it was in the past, I can say with a great degree of confidence that it won't happen. One of the reasons for which I think it won't happen is that the limit was not introduced by mistake, so the impact was analyzed before introducing it. Another reason is that, at least in your scenario, you can workaround this limit by creating a DG, adding 200 proxy addresses on this DG and make your mailbox a member of the DG.

Best regards!

Actually, a PM on the Admin team has replied to the Technet complaint and indicates this it is a valid issue.


Another person has posted links to Microsoft documents from 2013 indicating email aliases are unlimited.

This may only be a portal programming problem that will be hopefully corrected soon.


Yes, Nino has promised to get to the bottom of it. Once we have any info I'll reply here as well.


This article was updated to reflect the change in recipient proxy address limit.


Nino just posted another comprehensive update on the Answers thread: Read this reply

UPDATE: Unwelcome resolution.

The only option for any kind of solution was to create multiple Distribution Groups for individuals requiring more than 200 "proxy addresses" or aliases. It's the most stupid thing I've ever had to do in all of my 30 years of administration experience. I now have four, count 'em, FOUR distribution groups specifically for ME that contain 100 or more addresses in unequal alphabetic divisions.

I now accept that there may have been a limit previously however I was not even close to halfway at only 416 of some supposedly high number of 1200-1300 or more. Suddenly I was shown this popup in September 2016 that mandated no more than 200 addresses were acceptable after I had been well over 350 for years so I know this was a conscious decision by a bureaucrat somewhere at Microsoft. There is no other possible conclusion. Furthermore, I sincerely doubt this was carefully considered whatsoever.

There has to be a better way — if sensibility could ever prevail! If only Microsoft could find some way to incorporate WILDCARD addresses, this problem would hardly occur. Yes, I've seen the supposed "workarounds" for wildcards but it shouldn't be required. As always with Microsoft, I am once again disappointed, almost as much as with the Edge "browser" that some bureaucrat at Microsoft laughingly thought was a good idea. Sigh.


Have you tried to use the plus-sign in your mail-address instead of aliases?

Then you only need one E-mail address on your mailbox.

For example, if you have the mail address

Then use when you register mail-address at HPE or etc.

All mail should be delivered to the mailbox with the alias





Thanks for the suggestion but I have just confirmed that plus sign addressing does not work with Office 365. It generates a "550 5.4.1 Recipient address rejected" error.