When sending an email to raise a ticket in Jira Service Desk or reply to a notification to add a comment with attachments over 25 MB, we get a response from bounce@atlassian.net saying that the Mailbox is not found.

This is quite misleading as the mailbox does exist and the mail is in fact bounced due to exceeding the size limit. Hence the email fails to get processed and we do not see anything in the JSD Email handler logs too.

Hence raising this FR to provide a better error description.