When an email bounces in general, it means it has been rejected by your recipient's email server. Basically, this means your email wasn’t delivered to the recipients’s inbox. There are various reasons why your email could have bounced, but by and large, they are divided into two main categories: “Hard Bounces” or “Soft Bounces.”

Here’s what you need to know about "hard" and "soft" bounces, when it comes to adjusting your email marketing efforts:

The terms “hard bounce” and “soft bounce” are commonly used as broad descriptions for whether or not the email address should be mailed to again at a later date.

Hard Bounce

Hard bounces are permanent email delivery failures.

A hard bounce occurs when your recipient’s email address is invalid or is no longer in use. Typically, the domain name (the bit after the @) no longer exists or it no longer has registered mail servers. But it could also be invalid due to typos, for example, “gmial” instead of “gmail.” 

A permanent bounce may be the result of an unknown user error, which is caused when an email address:

  • Is invalid because it doesn’t exist
  • No longer in use or has been deactivated, such as when someone abandons a free email account or leaves a company
  • Contains a typo that made it invalid (i.e., @gnail.com instead of @gmail.com)

It is important that you pay attention to your bounce rate and your overall list hygiene. 

If you are using Gist to send your emails, we automatically handle your contacts that hard bounce by moving them to a suppressed list, and won't receive emails from you in the future so your sender reputation remains in tact. This means that you don’t need to constantly keep track of bounced contacts and remove them from your list - we silently handle it for you in the background.

Soft Bounce

Soft bounces are temporary email delivery failures.

A soft bounce is an email that couldn't be delivered because of temporary reasons and you may be able to deliver another email to that address at a later date.

It could be bouncing because:

  • You have been blocked by the recipient’s inbox provider because too many users have marked your emails as spam
  • You have been blocked for being on a blacklist
  • The recipient’s mailbox is full or an attachment might be too large
  • The email account has been temporarily suspended
  • Of an unforeseen error or outage at the receiving mail server

If you are using Gist to send your emails, we will retry delivery for a few days before giving up on a soft bounced email. If the recipient clears their mailbox then your email will probably get delivered. Same goes if the recipient's mail server becomes operational again.

Try to keep your total bounce rate under 2% -- much higher than that, and you'll start noticing some deliverability issues.


I see a spike in my bounce rate. What happened?

Usually, this means that you somehow introduced a list of contacts that hasn't been used recently and contained a lot of old, inactive email addresses that no longer exist. You should take a hard look at the list of contacts you emailed or imported recently to make sure you didn't accidentally add in some old contacts who shouldn't be there.

It can also happen if your email happened to contain a phrase or link that triggered certain major spam filters. This is a temporary issue that you can resolve by avoiding that phrase or link in future emails.

Lastly, there is a chance that the spike is due to a block because of high spam complaints. These usually resolve themselves if you don't have a prior history of high complaint rates.

How can I reduce my high bounce rate?

As long as you are only using healthy email collection practices, you will see a low bounce rate. Some of the addresses on your contact list may no longer be in use or are deactivated and bounce due to natural list churn. Some people may sign up with a misspelled address (like josh@gnail.com). It's normal to see 0.5-1% of your emails bounce due to these normal factors and that's just fine. However, if you are seeing a high bounce rate, it's likely because there is an issue with how contacts are being added to your contact list or perhaps they're not being sent emails often enough. Listed below are methods you can start using today in order to cut down on your bounce rate.

  • Use a double opt-in
  • Add a captcha to form
  • Send emails in set, regular intervals
  • Set up engagement management workflows
  • Use a real-time verification service as an extra safeguard

I have a valid contact that bounced. Why did that happen?

Usually, when this happens it is because the recipient's inbox provider decided to block the email you sent for one reason or another. This is a temporary error that should resolve itself, assuming the contact is valid.

However, in some rare cases, the inbox provider will make a mistake and give us a misleading bounce code saying the address is invalid when it was really bounced for another reason. If this happens, we'll take the inbox provider at their word and treat the account as invalid (hard bounce), even if this isn't true. If you know a specific bounced address is valid, reach out to support and we can take care of it for you.