How long, on average and at maximum, does it take an email Alias to become active on Microsoft 365-hosted Exchange?

Question

This is similar to a question asked over at Microsoft Answers: https://answers.microsoft.com/en-us/outlook_com/forum/oaccount-omyinfo/how-long-does-it-take-for-alias-to-be-created/a7f0adc1-de07-46dd-ae63-94db51e2bfd5, but I don't see a clear answer to that either. Also, is time for an alias to go live different for internal and external senders?

I created an alias and kept getting errors when external systems tried to send for about an hour. I tried again about 7-8 hours later and it was working. There is NOTHING as far as I can tell in the Exchange Admin Center GUI that indicates there will be any delay. I'm used to various features sometimes taking a few minutes to become available, but not hours. At a minimum, it seems there should be a note to this effect on the window where you can add email aliases.

Did I get lucky that it was usable in 7-8 hours, in that it might have needed as long as 24, or would it definitely have been ready after, say, 2 or 4 hours? Can anyone provide clarity on this? We need to know how long the typical lag is and how long it is at worst and if it's possible to predict the time (e.g., maybe these refresh once per day at midnight in somebody's timezone). This is basic needed knowledge for anything that takes time so we can plan and so we can know there must be an error or if we are just still in the standard lag window and to keep waiting. This info should be readily available to all admins for everything that isn't near-instantaneous.

Thanks,
Colin

Answer 1

There are no metrics for that and no defined amount of time.
Typically, its any where from 15 minutes to an hour, but maybe longer if 365 is having issues.

You can check the portal Health Dashboard for any known issues:

https://portal.office.com/adminportal/home#/servicehealth

If you continue to see delays, then you should probably open a ticket with 365 support.