Why do emails bounce?

Why do campaign emails bounce and what you can do to stop it from happening.

Reio Suun avatar
Written by Reio Suun
Updated over a week ago

Firstly, let’s take a look at what a bounce is.

A bounce is a situation where your email cannot be delivered to your recipient. Whenever that happens, you’ll get a report back in your inbox with the details of the bounce. You may have noticed similar reports like the one below in your inbox.

Bounces can be split into 2 categories - hard bounces and soft bounces.

Hard bounce

A hard bounce happens when the email address you’re trying to send an email to is no longer valid or has never existed.

Hard bounces can be avoided by cleaning your lead lists with verification tools before importing them into your campaigns and sending out emails. It is very important from a domain health and deliverability perspective that you avoid as many hard bounces as possible.

Other than that, there is not much else you can do to avoid hard bounces.

Soft bounce

Soft bounces are less common and a bit trickier to troubleshoot. Soft bounces happen when the recipient’s email is valid, but it cannot be delivered due to other reasons. The most common soft bounce reasons are:

  1. Attachments in the email triggering a spam filter and not letting emails go through. To fix this, make sure you are sending emails in plain text with nothing added to them.

  2. Spam words in the content of the email. Avoid special characters, non-Latin letters and spam trigger words like “earn $”, “credit card”, “FREE” etc. Avoid salesy language as much as possible.

  3. The recipient’s inbox is full and is unable to receive any emails. In this case you should wait and try sending them an email again later.

  4. Low sender reputation. If all of the reasons described above have been ruled out the most probable cause is a low sender reputation.

    In this case, the best course of action would be to stop your cold outreach and only let warmup run for a few weeks. After a few weeks you can start sending cold emails again and monitor if there is any improvement in bounces. Also, consider lowering your overall cold outreach volume.

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