High hard bounce rates are bad news for everyone. It means you have a large number of users with invalid email addresses. Repeated attempts to send to invalid email addresses will tarnish your brand's reputation and get Intercom's sending domains blacklisted. This affects deliverability for all our customers.  

We want to make sure that your content is reaching its intended recipients. Below we'll show you how to maintain a healthy bounce rate and ensure you don't collect invalid sign-ups.

What is a bounce?

A bounce is a message which has not delivered successfully. There are two types of bounces: hard bounces and soft bounces.

A soft bounced message is a temporary failure in delivery which can be caused by mailboxes being full or mail servers being offline.

A hard bounced message is a permanent failure in delivery. For example, a message could hard bounce when: 

  • The email address does not exist on a server.
  • The domain name doesn’t exist. 
  • Or the recipient has blocked delivery.

When you send a message we automatically remove addresses that hard bounce from your audience list for that message. And we don't attempt to send to those addresses again. We do this as continued attempts to deliver to invalid email addresses can harm Intercom's sending reputation.

How did you get invalid email addresses in your app?

  1. Typos: These are very common and can happen if you have no email validation at sign-up or no double entry. Entering details twice can reduce and prevent errors.
  2. Tests: You might use test email addresses in your own app, e.g: 123@web.de 123456789@gmail.com or similar. In this case we recommend that you set up a test app and only use email addresses ending in @example.com, as these will be filtered automatically.
  3. Old Lists: If your lists are aging, you might find that messages to some email addresses don’t deliver anymore. Your contacts at a particular company might have changed jobs or the company might have gone out of business. You should clean your user list of old, disengaged users once every 6 months. Neverbounce built an app to help clean your email list in Intercom. Other services you can use include Kickbox and Webbula.

How to view users who have bounced

When Intercom has tried to deliver a message but receives back a permanent error (bounce), that user or lead will be automatically removed from the audience for any further email messages - you don't need to worry about those users or leads causing repeated bounces in the future. If you have a high bounce rate, pay attention to where those bounced users came from. If all bounced users are from a specific source, that might indicate a larger issue. 

To see which users have bounced for any message you can click on the bounced stat on the message page itself:

You can also view all bounced users by filtering your main user list for "has hard bounced is true".

How to prevent invalid sign-ups

Implement confirmed opt-in

Have you ever signed up to a website and been asked to verify your email to complete your sign-up? That's confirmed opt-in. Confirmed opt-in proves that your new sign-up owns the email address and that it's valid. It also gives you permission to send emails to that address.

Implement email validation at sign-up

You can implement email validation at sign-up to check if email addresses are real. This helps prevent invalid email addresses from joining your app. Some common patterns of fake email addresses are:

  • Random patterns (asdf, abcd, 1234, qwerty)
  • Obscene patterns (duckyou, duckoff)* (We're being creative here, you get the idea! 😉  ) 
  • Don’t want mail patterns (nospam, noemail, goaway, leavemealone, nothanks, generic)

One of the simple ways you can validate email addresses is with some simple regular expression code (RegEx) in the code for your sign-up flow. You can see some examples of this just here. You can employ a third party service for this too: BriteVerify, Neverbounce or Mailgun.

Clean your Intercom people list

We recommend that you keep on top of your people list. If a user or lead hasn't interacted with your platform in a few months, it's likely time to say goodbye.

However it's worth noting that deleting a user from Intercom is a "soft delete". They will disappear from your user list and they won't count towards billing. If that user comes back to your app and signs in, we restore their details. 

How to delete inactive users

You can filter your user list to select the users you'd like to delete. For example, you might might want to filter for users or leads who were "Last seen more than 180 days ago."

Send messages to engaged users

Sending large volumes of email to disengaged users can actually damage your brand and your sender reputation. It's best practice to send messages to engaged users. You can target customers who were "Last Seen" and "Last Heard From" in your app recently, for example. 

These tips should help you better engage with your users and leads. For more tips, see our email marketing best practices.

If you're having trouble, get in touch by mailing us at team@intercom.io and we'll be able to help you through.

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