Too Many Recipients Error for emails to external recipients

An email was sent from a user (using the email address linked to their Discourse account) to several recipients, including a Discourse group alias.
The email was rejected with the Email::Receiver::TooManyRecipientsError error.

Why would Discourse care about the number of recipients if they are external addresses? Is it normal for the email to be rejected?

I think this will have triggered the error; this is an anti-spam and anti-abuse guard.

How many members are in that group?

  1. I don’t understand what you say is triggering the error.

Hm, 17 isn’t that much, but it’s more than the default allowed.

What is this setting set to on your forum?

Does changing that to >17 changes anything?

Or, if you were to try it without that discourse group alias, does it work then?

If so for either, that would confirm my suspicion it’s this an anti-spam measure throwing the error.