How do I find emails that failed to send?

To find emails that failed to send, the exact steps depend on which email app/service you’re using. Here are the most common places to check:

Gmail

• Open Sent and look for messages without a Delivered confirmation.
• Check Drafts for messages that never left.
• Look at the Outbox in the Gmail mobile app if you were offline.
• Search for error-related terms like: failed, bounce, undelivered, mail delivery subsystem.

Outlook / Microsoft 365

• Go to Sent Items and Outbox.
• Check for Non-Delivery Reports (NDRs) or bounce-back emails from postmaster.
• In Outlook desktop, also check whether the message is still stuck in Outbox if the app was closed before sending.

Apple Mail

• Check the Outbox mailbox.
• Look for bounced messages or delivery failure notices.
• If using IMAP, verify the message is in Sent and that no error appeared after sending.

General ways to identify failed emails

• Bounce-back email from the recipient’s mail server
• Message remaining in Outbox
• A status/error message such as:
  • “Message could not be sent”
  • “Delivery failed”
  • “Recipient address rejected”
  • “Server unavailable”

If you mean checking on a mail server or in logs

You may need to look in:

• SMTP server logs
• Mail queue
• Message tracking logs
• Bounce reports / NDR reports

If you tell me which email service or app you’re using, I can give you exact steps.