BouncesIn your reports, you may see “bounces” but what are they?

A ‘bounce’ means that your email was sent to a specific address, but the mail server that received the email for that person has sent it back, saying it could not be delivered.

Soft Bounce

A soft bounce is an email message that gets as far as the recipient’s mail server (it recognizes the address) but is bounced back undelivered before it gets to the intended recipient. A soft bounce might occur because the recipient’s mailbox is full, the server is down or swamped with messages, or the message is too large.

If an email has soft bounced in the last 5 campaigns without any trackable activity like an open or a click (and if those 5 campaigns took place over more than 2 days) it will automatically be converted to a hard bounce and be removed from your list.

Hard Bounce

A hard bounce is an email message that has been returned to the sender and is permanently undeliverable. Causes include invalid addresses (domain name doesn’t exist, typos, changed address, etc.) or the email recipient’s mail server has blocked your server.

Servers can sometimes interpret bounces differently, meaning a soft bounce on one server may be classified as a hard bounce on another.

Our email sending application automatically moves subscribers that hard bounce into a “Bounced Subscribers” category, so they don’t receive future campaigns.

Here’s a full rundown of other types of bounces you might see:

[accordion title=”Auto Reply (AR)” is_open=”yes”]These are soft bounces caused by an automatic response from the recipient, for example “Out Of Office” messages. The email is still actually delivered to the inbox, and once the subscriber opens the email (and is recorded), the bounce is removed from your reports.[/accordion] [accordion title=”General Bounce (GB)” is_open=”no”]The email server could not deliver your email message, but the bounce processing tool could not determine a specific reason for the bounce. Normally that is because the bounce message from the recipient’s server was very broad. We treat these as soft bounces.
Example: “Subject: Undeliverable mail”[/accordion] [accordion title=”Transient Bounce (TB)” is_open=”no”]The email server temporarily can not deliver your message, but it is still trying.
Example: “Warning: message still undelivered after 4 hours. We will keep trying until message is 2 days old”[/accordion] [accordion title=”Mail Block – Relay Denied (MBRD)” is_open=”no”]Indicates that the recipient’s email server is blocking email from our email server.
Example: “551 relaying denied”[/accordion] [accordion title=”Non Bounce (NB)” is_open=”no”]We determined that the message was not a bounce. This could be a recipient reply, or maybe a bounce format that we didn’t recognize.[/accordion] [accordion title=”Mail Block – General (MB)” is_open=”no”]Indicates that the recipient’s email server is blocking email from our email server.
Example: “550 Message REFUSED by peer”[/accordion] [accordion title=”Mail Block – Known Spammer (MBKS)” is_open=”no”]Indicates that the recipient’s email server is blocking your email because it believes you are a spammer.
Example: “REJECT Known SPAM source”[/accordion] [accordion title=”Mail Block – Spam Detected (MBSD)” is_open=”no”]Indicates that the recipient’s email server is blocking your email because the message appears to have content that looks like spam.
Example: “550 Possible spam detected”[/accordion] [accordion title=”Subscribe Request (SR)” is_open=”no”]A message has been sent back to the bounce address, looking to be added to your list. Since actual people would not normally know this address, these messages are just considered soft bounces.[/accordion] [accordion title=”Unsubscribe Request (UR)” is_open=”no”]In the same way as Subscribe Requests, these messages to unsubscribe sent to the bounce address are considered bounces. Actual subscribers will click the unsubscribe link or use the ‘reply-to’ address.[/accordion]

What Can You Do?

[checklist type=”checked”]
  • Keep your subscriber lists clean, check each list for incorrectly formatted addresses, invalid domains and typos
  • Use double opt-in, allowing each address to be validated by the subscriber before it can be added to your list
  • Monitor delivery rates by domain such as AOL, Hotmail, Yahoo, Earthlink and others
  • Test your emails by sending your campaign to your entire list, send a test to yourself and others