Customers using office365 as their SMTP server might run into quota issues:
They will see messages such as:
554 5.2.0 STOREDRV.Submission.Exception:SubmissionQuotaExceededException; Failed to process message due to a permanent exception with message The message can't be submitted because the sender's submission quota was exceeded. SubmissionQuotaExceededException: The message can't be submitted because the sender's submission quota was exceeded. [Hostname=XXXXXX]
office365 has a hard maximum of sending 10.000 emails a day but also a rate limit of 30 messages per minute. See this MicroSoft page for the latest numbers
If you get errors like this verify your daily sent emails if they don't reach the 10.000 maximum or the rate per minute.
The rate per minute can be influenced by the following 2 properties:
glide.smtp.one.chunk.per.send (default is false)
glide.smtp.max.per.job (default is 1000)
These to system properties can be adjusted and/or created.
Taking onto account that most instances have 2 SMTP sender jobs and they can run close together and thus still hit the rate per minute.
Be aware that this is not a Servicenow restriction, you should contact your email administrators for details on how/when these quota's were reached.
Tips for reducing the amount of emails
Scheduled reports can contain a lot of emails: check if internal mailing lists can be used to limit the emails sent per report
Use group email addresses referring to internal mailing lists (although this has a negative effect if group members are removed from a group, but not from the internal mailing lists. verify if your internal processes take this into account.