Do I need to delete soft bounces from my list?

Not immediately. However, if an address soft bounces consecutively over a long period (e.g., 5 times in a row), it's best practice to suppress it.

Can a soft bounce become a hard bounce?

Yes. If the mail server exhausts its retry attempts (usually over 2-3 days) without success, the soft bounce is recorded as a permanent failure.

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Soft Bounce Temporary delivery failure

temporary Concept

Meaning

A soft bounce is an email that failed to deliver due to a temporary issue, such as a full mailbox or a server being temporarily unavailable.

Common causes

The recipient's mailbox is full.
The receiving email server is temporarily down or overloaded.
The message is too large.

How to fix

In most cases, your mail server (or ESP) will automatically retry sending the email for up to 72 hours.
If a soft bounce persists across multiple campaigns, treat it as a hard bounce and remove it from your list.
Ensure your emails are not excessively large.

Provider notes

Amazon SES. SES automatically retries soft bounces. If it cannot deliver the email after a certain period, it stops trying and you may receive a notification.

Example bounce

452 4.2.2 The recipient's inbox is out of storage space.

FAQ

Do I need to delete soft bounces from my list?: Not immediately. However, if an address soft bounces consecutively over a long period (e.g., 5 times in a row), it's best practice to suppress it.
Can a soft bounce become a hard bounce?: Yes. If the mail server exhausts its retry attempts (usually over 2-3 days) without success, the soft bounce is recorded as a permanent failure.