Should I ever retry a hard bounce?

No. Retrying hard bounces tells ISPs that you do not maintain your list, which will severely damage your sender reputation.

How do hard bounces affect deliverability?

High hard bounce rates signal to mailbox providers that you are a spammer or have poor list acquisition practices, causing your emails to be routed to the spam folder.

← Error library

Hard Bounce Permanent delivery failure

permanent Concept

Meaning

A hard bounce is an email that has failed to deliver for permanent reasons, such as the recipient's address being invalid or the domain not existing.

Common causes

The recipient's email address does not exist (typo or deleted account).
The destination domain does not exist.
The receiving server has permanently blocked delivery.

How to fix

Immediately remove hard bounced email addresses from your mailing list.
Implement double opt-in to prevent invalid addresses from entering your list.
Regularly clean your email list to remove inactive subscribers.

Provider notes

Amazon SES. SES requires you to keep your hard bounce rate below 5% (and ideally below 2%). Exceeding this can lead to account suspension.

Example bounce

550 5.1.1 The email account that you tried to reach does not exist.

FAQ

Should I ever retry a hard bounce?: No. Retrying hard bounces tells ISPs that you do not maintain your list, which will severely damage your sender reputation.
How do hard bounces affect deliverability?: High hard bounce rates signal to mailbox providers that you are a spammer or have poor list acquisition practices, causing your emails to be routed to the spam folder.