Some of the email messages you have sent through Gmail might not get delivered at all. There could be a problem with the recipient’s email address, their mailbox could be full or maybe the mail server could be specifically blocking your emails due to the content of the message.
When an email message is returned, you get a bounce-back notice from MAILER-DAEMON@gmail.com and it will always contain the exact reason for the delivery failure along with the SMTP error code. For instance, an error code 550 indicates that the email address doesn’t exist while a 554 indicates that your email was classified as spam by the recipient’s mail server.
It is important to keep track of your bounced messages and remove all undelivered email addresses from your future mailings as they may adversly affect your sending reputation.
Mail Merge keeps track of all your bounced messages in Gmail but if you are using mail merge yet, here’s an open-source Google Script that will prepare a list of all email addresses that have bounced inside a Google Spreadsheet.
Here’s how you can get started:
- Go to labnol.org/bounce to make a copy of the Google Spreadsheet.
- Click the Gmail menu (adjacent to Help) and choose Bounce Report.
- Allow the Google Script to access* your Gmail account.
- Watch as the Google Sheet is populated with bounced addresses.
PS:The sheet uses an open-source Google Script that runs inside your own account and doesn’t share even a byte of data with anyone.
The email bounce report includes the email address that bounced, the reason why that email failed to deliver and the date when the bounce occurred. The spreadsheet will also have a direct link to the bounced message received from MAILER-DAEMON@google.com.