Troubleshooting steps in the case of Email delivery issue.
This can be troubleshot on 3 main topics, if the sender has not received any bounce back or non delivery report.
1. Each Google Apps account can be logged in from the gmail web interface and if the sender is using Outlook, in this case you can login to the web interface and confirm the affected email is there in the sent item/ sent mail of the Gmail.
– If you could not find the email in gmail sent item/ sent mail means email never reached to Google to execute the email delivery towards the recipient.
2. If you got the email in gmail’s sent item/ sent email, collect the message header of the email and perform the Email log search.
– Collect message header (Message-ID): https://support.google.com/mail/answer/22454?hl=en
– Email log Search: https://support.google.com/a/answer/2618874?hl=en
– With this you can see the final delivery status of the email from Google server to the recipient server
3. This topic is based on the result you got in the email log search.
– If the status is rejected/ un-delivered, which means the Google server found the issue while delivering the email and you can see the most possible reason in the logs only.
– If the status is the delivered, which means the recipient server has accepted the email data from Google server to process the email further for delivery.
After the 3rd stage, we do not have any further information about the email status, as the data is accepted by the recipient server and what recipient server do with that data Google con not get that records, as Google do not have access or control on the external recipient server.
In that case we suggest you to report the issue to the recipient server IT and submit the Email log search and message header of the affected email to begin the troubleshooting.