What is Email Bounce?


A bounce message means when your message not deliver to the receipt or NDR. An email bounce when your email was not able to delivered or send and bounce back to the sender. That time you think why? You setup everything properly and sending email from your mail server sudden you get back your message or email, there may be various causes that why your email is bounced. There is main two types of bounces hard bounce and soft bounce both are somehow different from one another, but both happens when your messages do not deliver due to technical error.

Types of bounces:

There are following types of bounces

  • Hard Bounce: When it comes to Hard Bounce, it’s the permanent bounce error, but it can be cause by the filters of email for security then reason behind this filtration is to protect the reputation of email sender.
  • Soft Bounce: When it comes to Soft Bounce it indicates the temporary problem or error, or soft bounce is a temporary technical error. Your recipient soft bounce can get future emails from you.
  • Pending bounce: It is also caused by temporary technical error from sending or receiving email server management.
  • Global bounce: A hard bounce or permanent bounce for the reason of technical error it includes unknown user or may be exhaustive mailbox.

Difference between the two:

There is the main following difference between hard and soft bounce

Hard bounceSoft bounce
Couldn’t be delivered for the permanent errorCouldn’t be delivered due to temporary error
May be fake email addresses, domain is not real domainEmails may be full or email file may be big in size
Might be recipient’s server will not accept emailsKeep an eye on addresses
Remove all the contradictory emailsIf getting error and popping up again and again remove them
Email Could be a hard bounce but it is permanent collapse Maintain your bounce rate 2%
Same domain or email don’t exist whenIf much higher than you will face deliverability issues
complicatedNot complicated
Email server blocked youBut usually, crucial

What are causes of hard bounce? Hard bounce may happen due to several reason when

  • The recipient not exist: You often see the mysterious text error like 550 5.5.1 server error, this is because of when you try to send an email to the email address that actually does not exist or the domain name. The reason behind the email address not exist can be, if someone give you email address maybe it removes from the company because he/she left the office, and you trying to send email message on that nonexistent email address so it would be hard bounce. Keep double check maybe you mistyped the email address, hence you can remove it from your email list.
  • Email is blocked by server: Email marketing and delivery has been changed modern email filters cease your email as unwanted. It can may be unproper setup, set up properly SPF, RDNS, DMARC and fresh domain name.
  • Your mailbox is full: Everything has its quota limit when you try to overload it, that would be definitely spew! YES, same case with your email box that has specific quota, when it reaches to its limit the other emails fall into bounce category.

What are causes of soft bounce?

It indicates as temporary error and harmless there are following reasons behind soft bounces:

  • DNS not setup properly/ failure: DNS failure happens from receiving side it indicates with some issues with domain name server system and message could not be delivered. Likely, misconfiguration, temporarily error with the server or its not proper add the DNS sometimes it happens when the domain name you provide not exist, connection time out etc.
  • A bulky message: The mailbox has the capacity limit but when you try to overload the server or mail box by send a large text of message it will be the reason of bounce because ISP’s do not allow large attachments and messages. ESP’s try to send over again and again but when it not sends by trying several times, it would be permanently rejected.
  • Flooded inbox: ISP’s put some limits on email delivery limit to prevent flooded inbox with spam text.

What is average rate of bounces:

The average bounce rate among all the industries

Hard bounce average rate0.40%
Soft bounce average rate0.58%

Recommendations for preventing bounce:

  1. Remove hard bounce
  2. Make sure your email list is clean
  3. Track your email deliverability service
  4. Send your emails on regular basis
  5. Authentication
  6. Use preference link
  • Remove hard bounce: when you face a hard bounce, simply eliminate the email address from your email list, try to avoid sending more emails to this address because it will definitely affect your email deliverability and will increase bounce rate more and more and you will be flagged in spam filter.
  • Make sure your email list is clean: Having hygiene good email list and cleaning up regularly will maintain your email list and will also decrease bounce rate and will keep 100% delivery with 0% bounce rate. Get rid of unsolicited emails list and only have clean and good email list that is up-to-date.
  • Track your email deliverability service: High bounce rate will increase your bad sender reputation. Never compromise to be on top for your email performance and never let it to spoil or harm your email deliverability. The longer you put your bounce issues on pending or unsolved, the big chance of having the bad reputation of your sender. Always try to check on your campaign result.
  • Send your emails on regular basis: This is the main reason of your high bounce rate because you do not send emails daily to your subscribers and not interacting them regularly. As a result, higher engagement lower bounce rates.
  • Authentication: It will show that you ate a legitimate sender and show receiver you are sending legal emails.
  • Use preference link: It will give your subscribers control over when they are receiving from you, it will also encourage your receiver to update their email addresses.

Conclusion: The reason behind (Why bounces occurred what are they) all the details above I mentioned is only to keep check on your email deliverability to prevent bounces, otherwise you will face hurdles while sending emails. Bounces do not have any rocket science, the simple reason is may be quota issue or you do not setup properly RDNS, SP and DKIM or the email addresses and domain name you are using not exist anymore. I also mentioned how to prevent bounces, you can follow these steps to decrease the rate of bounce in your email delivery service and to ensure smooth email delivery without any barrier.