Soft bounce

A soft bounce is a delivery failure the receiving server describes as temporary. Typical causes: the mailbox is over its quota, the message is too large, the server is overloaded or down for maintenance, or the receiver is applying greylisting and asks the sender to try again later. Mail servers usually retry a soft bounce for a while before giving up.

Soft bounces matter less than hard bounces, but they are not noise. A repeated soft bounce from the same address over several days often means the mailbox is abandoned, which is a dead address by another name. A wave of soft bounces from many different domains at once is a different story: it can mean a receiving network is deferring your mail because it does not yet trust your sending address, a common experience for a new mailbox sending too much too soon. In that case the fix is on your side, in volume and pacing.

In Seegnals bounces are shown in campaign stats and count towards the bounce shield threshold. Keep an eye on which addresses bounce repeatedly and remove them; a prospect whose mailbox has been full for two weeks is not going to read the third follow-up.