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Bounced Email


What is a bounced email?

When a recipient’s email server notifies you that your email was not delivered, that’s a bounced email.

Bounced emails both lower your potential conversion rates (i.e. sales) and negatively impact your IP reputation, which can cause your emails to get blocked, flagged and/or blacklisted.

It’s important to remove bounced email addresses from your sending lists.

What causes bounced emails?

There are two types of bounced emails: soft versus hard.

What is a soft bounce

A soft bounce is a temporary issue that is preventing your email from delivering. This can range from the recipient’s email inbox being full to the recipient’s server not being able to process the delivery, for example. You’ll see a soft bounce notification code that starts with a “4xx.”

A soft bounce typically resolves to “delivered” within 24 hours.

While these temporary issues typically resolve themselves, keep in mind that five consecutive soft bounces can turn into a hard bounce. And a hard bounce can definitely impact your IP reputation (while a soft bounce has less of an impact).

What is a hard bounce

Speaking of a hard bounce, this is when the delivery issue is permanent, such as an invalid email address. You’ll see a hard bounce notification code that starts with a “5xx.”

A hard bounce is considered a permanent failure.

What causes a hard bounce

Depending on the type of bounce, the cause can be a range of issues, including (but not limited to):

  • Invalid email addresses
  • Sender IP reputation
  • Mailbox is full
  • Mailbox is inactive
  • Email message is too large
  • The domain name does not exist
  • Blocked due to content
  • Recipient’s email server down or offline
  • Mailbox not configured correctly
  • Recipient’s email server sent too many messages during a period of time
  • Aggressive spam filters

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