Bounces: Why a contact didn't get your email

Reasons why an email can bounce, and what you can do about it

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Bounces: Why a contact didn't get your email

Bounces are contacts that didn't get the email that you sent to them. The email "bounced" out of their inbox for a few possible reasons. We collect the data that their Internet Service Provider (ISP) gives us in your email reports and categorize your bounces by type. 

We recommend that you manage bounced email addresses for every email campaign you send.

How Bounces Work

Constant Contact's bounce system works like this: 
  1. An email is sent from one of Constant Contact's mail servers and is received by the mail server of an ISP or Network Administrator.
  2. The ISP/Network Administrator can either send the email to the recipient or bounce it back to Constant Contact for various reasons.
  3. If the email is bounced back to Constant Contact, it comes back with error messages that our system uses to categorize why the email bounced.
  4. If the system can categorize why the email bounced, it places the email in one of the five definite categories: Non-existent, Mailbox Full, On Vacation, Undeliverable, or Blocked.
  5. If the system cannot determine why the email bounced, it places it in the Other category.
  6. If an address consistently bounces as non-existent, it will be placed on an internal hold. These will be categorized as Suspended.

Because not all ISPs use the same error messages, our system may categorize a message incorrectly. If you think this may be happening to some of your bounces please contact Customer Support and explain why you believe the listed bounce reason may be wrong.


Types of Bounces

There are six categories for bounces and they all mean something a little different about what happened to your email and what steps you should take next.

Recommended for removal: Regularly removing these addresses your account can help promote healthier lists.
  • Non-Existent - These bounces happen when the contact's Internet Service Provider (ISP) says that an email address doesn't exist. It's like the post office saying there's no one with that name in the building. You may want to double-check these addresses for obvious typos and fix them, find another way to get in touch with the contact and see if they have a new email address, or if the address continues to bounce over time, remove it from your lists
  • Undeliverable - Undeliverable messages are like a busy signal. When we attempted to send the email, the Internet Service Provider wasn't responding. We keep trying to deliver the email for up to 3 days. If there's no response after that, we label it a bounce. You can continue sending to this email address for a bit since the ISP may fix things. However, if an email just keeps bouncing you probably just want to remove it from your lists and see if the contact has a different email address to try. 
  • Suspended- Sending email repeatedly to the same non-existent addresses can negatively impact deliverability. To help with this, addresses that consistently bounce as non-existent are placed on an internal hold to prevent us from sending to them again. Constant Contact will not attempt to send any emails to these “suspended” addresses. We recommend that you remove these addresses from your list.

Manage: These addresses may have bounced, but you may not want to remove them immediately.
  • Mailbox Full - When an inbox is just too full to continue getting new email, the ISP sends back a Mailbox full message. Usually this happens with mailboxes that just aren't being checked that often. You may want to get in touch with the contact and find a better email address and, if this email address keeps bouncing, remove it from your lists
  • Vacation/Auto-Reply - Remember when I said that bounces are emails that "bounce" out of an inbox? Vacation and Auto-replies are the exceptions to this rule! When someone sets up an Auto-reply, a bounce message gets sent to us even though the email is actually delivered. That means you don't have to do anything. The message is just a way to let you know that the contact might not see your email for a while.
  • Other - Sometimes an ISP doesn't use a standard error message when they send back the bounce information. In that case we might not be able to tell exactly what they are saying about the bounce. We categorize these bounces as others. You can also get in touch with the contact to get a better email address and should probably remove it from your lists if it just keeps bouncing.
  • Blocked - When an email is blocked the ISP has decided not to deliver it, likely because it thought the email was spam. That could be because the ISP was concerned about something specific in the email or it rejects email from large senders. Go ahead and use the Spam Checker before you send your next email to reduce the chances of it being blocked because of content issues. If you are still getting blocked bounces from a larger domain (Yahoo, Gmail) go ahead and contact us. If it's a smaller domain or ISP, there are some steps you can take next.

Note: Due to a change in Yahoo policy, emails sent using a Yahoo address as the "From Email Address" will bounce as "Other".

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