Exchange Online to introduce External Recipient Rate Limit

[pablo007]

For those of you not using third parties to send out reports end of term letters etc. one to watch out for

 

 

MC787382 | April 26 - Beginning January 2025, Exchange Online will enforce a new External Recipient Rate limit of 2000 recipients per 24 hours, introduced in two phases for new and existing tenants. This limit is part of the overall 10000 Recipient Rate limit, aiming to prevent abuse of services. Organizations exceeding this limit should consider Azure Communication Services for Email.

[robintech]

Would prefer it if they restricted the tenant at a much higher level instead of per mailbox, couldn't spammers just switch mailboxes every hour

[pablo007]

They do, The current recipient rate limit for Exchange Online is 10,000 recipients per day. The recipient limit is monitored using a rolling 24-hour period. If the limits are reached then no emails may be sent from the email account that breached the limit until the recipient rate drops below the threshold.

[robintech]

Don't think we've ever got close to the 10,000 recipient limit then, 2,000 maybe if they sent a School closed and then an update on the situation on the same day.

We have custom limits for each group on sending which should notify and block before Microsoft block it.

[Rob_D]

I'm being a bit dense, but...

The 2,000 external recipients in a 24 hour period is per account (not for the whole tenant), right?

And what is a recipient? Does that mean I can send a million emails a day to the same email address and have it count as 1 "recipient"?

[pablo007]

A good article on the current setup here https://helpcenter.elearningforce.com/hc/en-us/articles/360015355257-Implications-of-Microsoft-Exchange-Online-limits-on-LMS365-Learn365-email-notifications

i admit deciphering the actual limits and what is a recipient etc. is a head scratcher..

[chaplic]

This is giving me a headache for client as we were planning to remove the on prem server and relay all though O365, happily sliding under the limits.

 

Now current plan is to install Exchange 2019(!) so we can get some DLP and then relay out via Azure Communication Services which is straightforward to do. Alas it does seem to do AV scanning (silently gobbled an EICAR far as I can tell) but no other functionality.