Common Mailserver Limits & Further reading
This page contains useful links for common mail servers that can help JEMHC customers understand why specific errors occur (eg relating to non-delivery due to large numbers of recipients):
Gmail
O365
https://docs.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits#message-limits
https://techcommunity.microsoft.com/t5/exchange-team-blog/customizable-recipient-limits-in-office-365/ba-p/1183228
https://docs.microsoft.com/en-us/exchange/monitoring/trace-an-email-message/trace-an-email-message