Campus Users may get intermittent errors when sending emails.
If you get an error while sending email, please retry after a few seconds, or minutes
Help Desk confirmed this issue to be campus-wide. Opening a ticket with Google.
Google opened Case #03233237, and confirmed that a lot of their customers were having the same problem. The problem has allegedly been fixed in the meantime.
Information Technology Services
Humboldt State University
Arcata, CA 95521