In general, a Bounce means an email can't be delivered to an inbox. "Hard" and "soft" designate the two groupings of failures; one is pretty permanent, the other might not be.
A hard bounce indicates a permanent reason an email cannot be delivered. There are lots of reasons that an email could be a hard bounce, but the core of it is that it's a permanent failure. You should remove all of these addresses from your list, Herefish will do that automatically and also indicate the bounce in your ATS.
Some common reasons for a hard bounce:
- Recipient email address does not exist.
- Domain name does not exist.
- Recipient email server has completely blocked delivery.
A soft bounce is an email that couldn't be delivered because of temporary reasons. Often email providers will continue to try to deliver the email a few times. Herefish will automatically remove treat an email that gets 3 soft bounces, as a hard bounce.
Some common reasons for a soft bounce:
- Mailbox is full (over quota).
- Recipient email server is down or offline.
- Email message is too large.
Ideally your bounce rate will be under 2.5%. If it starts to go higher than that, you'll likely start to have issues with delivery.
Hard bounces = permanent
Soft bounces = temporary