Hard/Soft Weekly Bounce Reporting

SMTP2GO improved weekly bounce reporting service has recently been enabled.

The weekly reports include only true, hard bounces. A hard bounce is an email address that has proven to be undeliverable, and will never accept email in the future.

The only truly accurate method of determining whether a bounce is hard or soft is to analyse the bounce message for positive or negative keyword phrases.

So… how do we do it?

When an email bounces, we  scan the bounce-back message against hundreds of specific known soft bounce keyword phrases, such as ‘Mailbox is full’, ‘SPF check failed’, and ‘We do not accept junk mail’.

If a bounce’s message includes any of our soft bounce keyword phrases, it is classified as soft.

If the bounce hasn’t already been classified as soft, we then scan the message against hundreds of specific known hard bounce keyword phrases, such as ‘Invalid email recipient’ or ‘The account does not exist’.

If a bounce’s message includes any of our hard bounce keyword phrases (and wasn’t already classified as soft), it is classified as hard.

Our classification system has a very high level of accuracy, and we’re sure it will be of use to anyone using SMTP2GO to send to mailing lists.