Hard Bounce vs. Soft Bounce: What Each One Does to Your List
A bounce is an email the receiving server sent back. Every list gets some. What matters is which kind, and what you do next.
The short version
- A hard bounce is permanent. The address doesn’t exist, or the domain doesn’t, and sending again won’t change that.
- A soft bounce is temporary. The mailbox is full, the server is down or busy, or the message was too large. A later send may go through.
What causes hard bounces
- A typo at signup, like gmial.com or a missing letter.
- An address that used to work: someone left a job, or abandoned an old inbox.
- A domain that doesn’t exist or can’t receive mail.
- A fake address typed in to get past a signup form.
What causes soft bounces
- A full mailbox.
- A receiving server that’s down or slowing incoming mail.
- A message larger than the receiver accepts.
Why bounces matter
Mailbox providers watch how often your mail hits addresses that don’t exist. A list full of dead addresses tells them you don’t keep it clean, and that can push your mail toward spam for the readers who do want it.
What to do
- Remove hard bounces right away. Most email platforms suppress them automatically. Check that yours does.
- Give soft bounces a few chances. If the same address soft bounces send after send, treat it like a hard bounce and stop sending.
- Find the source. A spike in bounces usually points to one signup form, one import or one event list. Fix it there.
Keep bad addresses off the list
The cheapest bounce is the one that never happens. Confirmed opt-in catches most typos and fake signups. For a single address that looks off, check it before it goes on your list.
The other kind of ghost
Bounces are easy to spot. Harder are the real readers who stopped opening months ago. They don’t bounce, but they drag down the engagement signals Gmail and Outlook use to decide where your mail lands.
In Letterhead, every newsletter sorts its readers into engagement groups, Ghosts included, and shows how many readers each group holds before you send. See the five reader types for what to do with each.
Frequently asked questions
Should I resend to a hard bounce? No. It won’t deliver, and repeated attempts look worse to mailbox providers.
Are role addresses like info@ more likely to bounce? Not always, but they’re often shared or unattended, so watch how they engage.
Can I check whether an address will bounce before I send? For one address at a time, yes: the email verifier asks the mailbox provider whether it accepts mail, with no signup.