Rate Limits for Exchange Email

Overview

Due to issues with compromised accounts being used for spam, the university has implemented rate limits on email sent from Tufts email accounts. These rate limits are designed to prevent Tufts email accounts from being blocked by others (such as Tufts Medical Center, Comcast, Verizon, etc).

Email accounts that send email to more than 1000 people within a 24 hour period will be blocked from sending email. Some existing email addresses have been whitelisted (for example announcement elists).

If you believe someone's issue with sending email is related to the rate limit, please include the full headers when submitting the ticket to IT@tufts.edu so that the issue can be resolved more quickly.

Forwarding Email

Any emails redirected or forwarded via an OWA rule will count as sent email for the purpose of the rate limit. For example, someone forwards to a gmail account using email rules, if they RECIEVE over 1000 messages they will hit the limit and they will stop receiving email. If they are forwarding to 2 other email accounts, they will his the limit after 500 messages, and so forth.

To avoid this issue with the rate limit, forwarding should be set up at the mailbox level via Tufts Tools. Users can change their forwarding settings at https://tuftstools.tufts.edu/cgi-bin/forward

Removing Rate Limit (Exchange On Prem Only)

To remove the limit, you have to remove the max recipient limit from Exchange Management Console, and then run a command in the shell to put the mailbox in a different policy. This can be done in any order.

Exchange Management Console:

Open up Mailbox Properties in Exchange.

Select Mail Flow Settings tab.

Delivery Options → Properties

Remove check for Maximum Recipients.

Exchange Shell:

Set-Mailbox -Identity UTLN -ThrottlingPolicy HighVolumePolicy