When a notification is sent with a large recipient list (50+ users in the To field), the email record is attached to the case successfully, but the recipients do not receive the email in their mailbox. We have verified the production logs and found no errors related to email processing.

I have also checked the recipient limit from Pega and Microsoft Graph and confirmed it is within the allowed limits. Still, we doubt if the issue could be related to the client’s SMTP server configuration. Please let me know if I am missing any configuration checks and provide guidance on what could cause the failure to deliver emails to recipient mailboxes.