Email Bounce Tracking
Bounces are handled for you automatically and you can view reports showing which email addresses bounced, when and why, with an exact error message from the email provider, such as "Email address doesn't exist".
The bounced emails report
When an email message cannot be delivered to an email address, it's called a bounce. There are lots of different reasons why emails bounce so, when it happens, a "return to sender" message (or, SMTP reply) is sent from the recipient's mail server to explain why. We process bounce replies and include them in the "Bounce Summary" section of your reports. Below, we'll give you an overview of the report and explain how we handle bounced email addresses.
The bounce summary report lists any email addresses that bounced, and the reason why. The error message returned is used to classify each email address as a soft or hard bounce, meaning a temporary or permanent delivery failure.
Hard bounce are permanent and mean the email address is no longer valid.
The "Bounce domains" tab, pictured above, shows you how many emails bounced for each domain you've sent to. This is useful for determining if you have delivery problems with any specific domains. If you notice a large number of bounces for one domain, it may indicate that your emails are being blocked by the ISP's receiving server.
One of the most important metrics to monitor after you've sent a campaign is the "bounce rate", which is the number of bounced emails divided by the total number of recipients the campaign was sent to.
A soft bounce is a temporary delivery failure. Your email campaign got as far as the receiving mail server, meaning the email address was recognized, but the message bounced back undelivered instead of reaching the recipient's inbox. Soft bounces can occur when the recipient's mailbox is full; the receiving server is down or swamped with messages; the message size is too large; the recipient's settings do not allow for email from the sender; suspicious or spammy content has been detected, and many more reasons. A hard bounce is a permanent delivery failure. When you get a hard bounce it means the recipient's email address is invalid or no longer in use. Typically the domain name (the bit after the @) no longer exists or it no longer has registered mail servers. But it could also be invalid due to typos, for example gnail instead of gmail.