Hard bounces, soft bounces and complaints: what each one means

After a campaign goes out, the report shows more than opens and clicks. It shows the emails that never arrived and the readers who did not want them. Those numbers are the ones inbox providers care about most, and they are the ones a sender can actually control. Here is what each one means and what to do when it moves.

Hard bounce: the address does not exist

The receiving server answered that there is no such mailbox. The address was mistyped, the person left the company, or the domain itself is gone. Nothing you send later will change that, so the only correct response is to stop sending to it. Every further attempt tells the provider that you do not clean your list, and providers hold that against every other email you send.

A hard bounce rate above two percent on a campaign is a warning. Above five percent, some providers start deferring or refusing your mail on the spot. If a list you imported bounces at that level, pause and clean it before sending again.

Soft bounce: the address exists, but not right now

The mailbox is full, the server was busy, the message was too large, or the provider is slowing you down for the moment. A soft bounce is temporary by definition, and a single one means little. What matters is repetition: an address that soft-bounces on three or four campaigns in a row has almost certainly been abandoned, and it is time to treat it like a hard bounce.

Complaint: the reader pressed the spam button

This is the number to watch most closely, because it is the one providers weigh most heavily. A complaint says that a real person saw your email and decided it did not belong in their inbox. Providers count complaints against the number of messages delivered, and the threshold they tolerate is small: around one in a thousand. Above that, your mail starts going to the junk folder for everyone, not only for the people who complained.

Someone who complains must never be emailed again, whatever list they are on. Most providers send the complaint back to the sender for exactly this reason, and a good sending platform unsubscribes the address the moment the complaint arrives.

What pushes complaints up

• An unsubscribe link that is hard to find. When leaving is difficult, the spam button is the easy way out.
• A long gap since the last email. People forget they signed up, and an email from a name they do not recognise looks like spam.
• A subject line that promises something the email does not contain.
• Sending to a list that was bought, borrowed or scraped. Those readers never asked to hear from you, and some of them will say so.

What to do after every campaign

Read the three numbers. Remove the hard bounces, note any address that has soft-bounced repeatedly, and look at the complaints one by one. If they come from one segment, one country or one source of signups, that is where the problem is. The fix is almost never technical. It is sending less often to people who did not ask, and more often to people who did.

MBX Reach does the mechanical part for you: an address that hard-bounces is suppressed automatically, a complaint unsubscribes the address from every list in the workspace, and both show up in the campaign report so you can see where they came from.

MBX Reach is email marketing for small teams: lists, campaigns, automations and reports, in six languages.