Why do Email Bounces back?

Why do Email Bounces back?


Why Do Emails Bounce Back, and How Can You Lower Your Bounce Rate?

Bounces of emails is part of your total delivery. But is important to understand why this happen and how to avoid.

In this article, you’ll learn:

  • What is a bounce back email?
  • What causes an email to bounce back?
  • How can you reduce your bounce back rate?

What is an email bounce?

An email bounce (or “bounce”) is an error you receive when your email has not reached the destination. normally you receive an automated message (Non-Delivery Report (NDR). from e-mail server with details talking about the specific problem.


To understand bounce back emails you need to know what are the steps to deliver an email.

1.   You address an email by filling out the “From” and “To” fields and click the “Send” button.
2.   Your email is sent to your SMTP (Simple Mail Transfer Protocol) server for delivery.
3.   The SMTP server checks your email with the DNS (Domain Name Server). The DNS is an address book for domain names and server IP addresses.
4.   Once your recipient’s server is located, the SMTP server send your email to their MTA (Mail Transfer Agent) to complete email delivery. 
5.   Your email is delivered successfully to your recipient’s inbox.
But sometimes, this doesn’t happen. 

What causes an email to bounce back?

There are some reasons for a email bounce back: fake email addresses, full inboxes, non-existing e-mail addresses, not responding servers.

Those reasons can be temporary or permanent. and you must know how to troubleshoot bounces, first you need to understand each type of bounce:

The are three types of bounce backs that disrupt the delivery of your email are:

1.   Hard bounce emails.

2.   Blocklisted emails.

3.   Soft bounce emails.


1. Hard bounce emails

A hard bounce happens when your email is permanently undeliverable to an email address.

The Reasons for a hard bounces include:

- Fake email address

- Incorrect email address

- Email blocked: Some domains (like governmental or institutional) have stricter spam filter settings.

It's not possible to fix hard bounce issues. What you can do is remove those hard bounced addresses from list. If you don’t start doing this, you have high risk of your emails being blocklisted.


2. Blocklisted emails

Nearly 88% of emails are considered spam.

Email blocklists are created by ISPs (Internet service providers) to filter harmful content, like malware or spam

Emails get blocklisted because certain things:

- Email volume
Spam complaints
Bad content: If you use some spammy words like (FREE)
High bounce rates


3. Soft bounce emails

Emails soft bounce happens when a server rejects an email temporarily. Most email services try to resend email messages after they soft bounce.

Reasons for a soft bounce include:

Mailbox full: If a recipient has too many emails and reaches capacity limit, your email will bounce back until there’s free space.

Email size: If you pack emails with megabyte-heavy images or include huge attachments, it might be bounced back if there’s a related filter in place

Server is down: An unreachable server may have crashed, been overloaded, or been under maintenance. This means you must wait to send the email to the address again.

Autoreply: If someone goes on vacation and sets an auto reply, your email will often bounce back.


How do you get off a blocklist?

- Wait some time: 
Being removed from a blocklist automatically after a predetermined time period.

- "Talk" with the blocklist: Submit a request.

Maintain your list clean: Removing dead-end addresses that have hard bounced — and never buying any contact lists.

Changing your ESP: If the IP assigned to you are compromised, change providers to stay off blocklists





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