Handling bounces

When an email is returned to the sender, it’s called a bounce. Bounces come in two types, and Letterhead handles both for you; this article explains what happens and where you can see it.

Soft bounces

A soft bounce is temporary — the recipient’s mail server received the email but couldn’t deliver it to the inbox. Common reasons:

1. The recipient’s mailbox is full.
2. The message is too large for the recipient’s mailbox.
3. The recipient’s email server is down or having issues.
4. The email was blocked by the recipient’s spam filter.

Soft bounces usually resolve themselves; providers retry a few times before treating the address as a hard bounce.

Hard bounces

A hard bounce is permanent — the email couldn’t be delivered because the address is invalid, non-existent, or blocked. Common reasons:

1. The address is invalid or doesn’t exist.
2. The domain has been closed or no longer exists.
3. The address is a known spam trap.
4. The recipient’s server has blocked the sender’s domain.

Hard bounces hurt deliverability — too many can get your domain flagged as a spammer — which is why cleaning invalid addresses off your list matters.

How Letterhead handles bounces

• Hard bounce: the address immediately moves to the Bounced (Cleaned) status. It receives no further emails and isn’t billed on your account.
• Soft bounce: Letterhead keeps sending to the address until it soft-bounces several times in a row, at which point it’s treated as a hard bounce and moved to the bounced status. The exact threshold varies by circumstance.

Each contact’s profile shows their bounce history (hard and soft counts plus mail-server reasons) along with which newsletters they’re suppressed from and why.

Seeing bounces in your reports

Your reports show hard and soft bounces as separate metrics, alongside the overall Bounces total:

• Edition metrics: each newsletter edition shows separate counts and rates for hard and soft bounces.
• Company analytics: cards show hard and soft bounce counts and rates across your newsletters.
• Newsletter Engagement Report CSV: columns break out hard and soft bounces beside the combined total.

A rise in hard bounces usually points to where a list came from, so it’s worth checking any recent import. Soft bounces often clear on their own. See what each report metric means.

Resubscribing a bounced address

We don’t recommend it — it’s best for the reader to subscribe with a different address. Letterhead suppresses Cleaned emails to prevent further delivery issues and protect your sender reputation. If you’re confident the address is now valid, you can ask Penpal to restore the reader by naming them by email address and the newsletter. Penpal checks and tells you what it found — whether they’re cleaned, whether the address is being held back and why, and whether restoring them lifts that — then asks you to confirm and give a reason. This works one reader at a time, on newsletters Letterhead sends itself. You can also edit the subscriber manually and change their status to Pending confirmation, save, then edit again to Subscribed.

For more on list health, see list cleanup and Working in Audience.