When you sent an email that can’t deliver to a mail server, the sent mail will reject to the sender. This process called Bouncing. If you manage an email marketing campaign, it’s possible to see a ratio called bounce rate. In the next paragraphs, I will explain the bounce rate and different bounce types.

What is Bounce Rate?

Bounce Rate is the ratio between bounced emails divided by total sent emails. Bounce Rate is a nightmare of email marketing campaign admins. By increasing bounce rate most Email marketing platforms stop sending your emails and maybe disable your account and on the other hand some mail servers will detect you as a spammer! Why?!

If your email marketing list contains many invalid emails, it shows you are using a low quality email list that users don’t enter their email addresses voluntary.

Different Bounce Types

As I mentioned before, due to cause of bounce we have 2 different bounce types. Hard Bounce & Soft Bounce.

What is Hard Bounce?

When you send an email to a recipient if the recipient email address didn’t exist your sent mail bounced to you as hard bounce. incorrect email addresses increase your hard bounce rate. When you receive hard bounce alert it means the email address domain name does not exist or username is unknown to the receiver mail server.

What is Soft Bounce?

While the hard bounce shows the email address is not valid, on the other hand, the soft bounce occurs typically when the message can’t deliver to the receiver temporarily.

Soft bounces may have several reasons, these are some of typical reasons for Soft Bounce:

  • Inbox is Full ( Over Quota )
  • Mailbox is not configured correctly
  • Inactive mailbox
  • Recipient mail server is offline
  • Recipient email server has been sent too many emails during a period of time
  • Email message is too large
  • Email message blocked due to content
  • Email message does not meet the recipient server’s policies
  • Email message does not meet the recipient server’s DMARC requirements for authentication
  • Email message does not meet the recipient server’s anti-spam requirements
  • Email message does not meet the recipient server’s anti-virus requirements
  • Email message does not meet the recipient server’s sender requirements
  • Email cannot be relayed between email servers
  • Email cannot be relayed for unknown reasons