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Email Bounce Back Messages

Email issues can be frustrating, and the bounce back message announcing that a message did not get through may seem cryptic. However, it can actually tell you where the problem lies and help you (and us) figure out why your email is not behaving.

This article will show how to approach some of the more frequent messages you might see.

Note: When contacting us for assistance with any email issue, please provide a sample of the message which has bounced back to you with the full headers enabled. This article has more information:

Click on the links below to jump into a category:


Common Outgoing Bounce Back Message

Bounce Back messageReasonResolution
SMTP 554
(rejected for policy reasons)

The domain or email address is blacklisted or detected as spam.

  • Review if the IP address is listed on the Spamhaus IP and Domain Reputation Checker.
SMTP 550
($toemail recipient rejected - ERR016)

The recipient is detected as spam, blacklisted, or has reached their email quota.

  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server.
SMTP 452 (fromemail sender rejected) The email limit has been reached. Too much email was sent from the server.
  • Attempt to send the email at a later time. 
SMTP 550 (fromemail sender rejected - ERR082)The sender is identified as spam, blacklisted, or has reached the email limit purposes.
  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server
  • Also, request to check with the recipient if your email address or domain is in their server's spam filter.
  • Attempt to send the email at a later time. 
SMTP 550 (fromemail sender rejected - ERR081)Domain or the email address is blacklisted.
  • The recipient has blocked your domain name or email address.
  • Request your email address or domain to be whitelisted on the recipient's server
SMTP 550 (fromemail suspect invalid mailer domain, please check your dns records - ERR006)The sender's email is detected as an IP address.
  • Check DNS records configuration. Possibly the DKIM or SPF record is not allowing incoming messages. Ensure all DNS records are updated.
  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server
  • Attempt to send them at a later time.
SMTP 550 (fromemail Suspect invalid mailer domain, please check your DNS records - ERR007)MX and A records are not configured.
  • Check DNS records configuration. Possibly the DKIM or SPF record is not allowing incoming messages. Ensure all DNS records are updated.
  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server
  • Attempt to send them at a later time.
SMTP 550 (fromemail Suspect invalid mailer domain, please check your DNS records - ERR008)Ensure that DNS is not failing. 
  • Check DNS records configuration. Possibly the DKIM or SPF record is not allowing incoming messages. Ensure all DNS records are updated.
  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server
  • Attempt to send them at a later time.
SMTP 550 (fromemail Suspect invalid mailer domain, please check your DNS records - ERR009)The A or MX records are invalid.
  • Check DNS records configuration. Possibly the DKIM or SPF record is not allowing incoming messages. Ensure all DNS records are updated.
  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server
  • Attempt to send them at a later time.
SMTP 550
($toemail recipient is invalid - ERR010)
The sender's email is detected as an IP address.
  • Confirm the email address with the cx and ask to verify the spelling of it.
  • Attempt to send them at a later time
SMTP 550
($toemail recipient is invalid - ERR011)
The recipient's DNS check failed.
  • Check DNS records configuration. Possibly the DKIM or SPF record is not allowing incoming messages. Ensure all DNS records are updated.
  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server
  • Attempt to send them at a later time.
SMTP 550
($toemail recipient is invalid - ERR013 and ERROR014)
The recipient's domain is not a valid domain name.
  • Check if the email address is correct.
  • Suggest he attempts to send them at a later time.

Error 550
You have reached the maximum number of messages per session.

The maximum allowed messages have been reached in that particular session.
  • Attempt to send them at a later time.

Error 550
The Domain Name System (DNS) reported that the recipient's domain does not exist.

  • The recipient's domain or email address does not exist.
  • The recipient's MX record is not set up.
  • The recipient's A record for the mail server is not set up.
  • Check DNS records configuration. Possibly the DKIM or SPF record is not allowing incoming messages. Ensure all DNS records are updated.
  • Contact the sender and check the reason for the email rejection.
  • Request your email address or domain to be whitelisted on the recipient's server
  • Attempt to send them at a later time.

UCE
(Unsolicited Commercial email ) strictly prohibited

The recipient is sending unsolicited emails to any person or persons the sender does not know or have prior explicit consent to send the message(s) to.

  • Suggest the use of email marketing tools such as Constant Contact.

Email Content-Related Bounce Back Message

Bounce Back messageReasonResolution
SMTP 421
(Temporary Rejection. Reverse DNS for IP failed)

SMTP Temporary rejection - The server couldn't identify the domain's PTR record.

  • Check if the Sender's IP Address has set up a reverse DNS before sending the email. 

SMTP 552
(Remote MTA $ip: A URL contained in this message is blacklisted by Spamhaus DBL. See http://www.spamhaus.org/dbl)

There is a blacklisted  URL in the body of the email.

  • Remove the blacklisted URL and send it again. 

SMTP 552
(virus-infected message rejected)

A virus in the message has been detected by Cloudmark

  • Set an opt-out option in your email.
  • Ensure that all email recipients are correct.
  • Contact HostGator Support if your emails are flagged erroneously.

SMTP 552
(virus-infected message rejected)

The email contains a file that is in a format not allowed by the server like: bat .btm .cmd .com .cpl .dll .exe .lnk .msi .pif .prf .reg .scr .vbs.

  • Set an opt-out option in your email.
  • Ensure that all email recipients are correct.
  • Contact HostGator Support if your emails are flagged erroneously.

SMTP 554
(Connection refused - IP)

The message is tagged as spam based on CSI.

  • Check the sender's IP address's reputation in Cloudmark Sender Intelligence (CSI).

SMTP 554
(Connection Rejected. Reverse DNS for IP does not exist)

Permanent rejection. The domain doesn't have a PTR record.

  • The incoming mail server has detected that the email is spam or the sender's IP address is blacklisted.

Quota/Limit Related Bounce Back Message 

Bounce Back messageReasonResolution

SMTP 421
(Server Temporarily Not Available)

The email queue is full.

  • Attempt to send the email at a later time.
SMTP 550
(fromemail max messages per session)

The email limit has been exceeded.

  • Attempt to send the email at a later time.

Email Recipient-Related Bounce back Message 

Bounce Back messageReasonResolution
SMTP 452 (toemail requested action aborted: try again later - GL/GL)Temporary failure. The recipient's mail server has greylisting setup.
  • Attempt to send the email at a later time.
SMTP 550 (fromemail sender rejected)Email address isn't correctly formatted (has no @domain).
  • Ensure that you entered the correct email address. 
SMTP 550 (toemail recipient rejected GL/BL)Permanent failure. The sender's domain or IP address is blacklisted.
  • Contact the email recipient. Your email address could have been blacklisted by accident. 
SMTP 550 (toemail recipient rejected)The To email address doesn't exist.
  • Check if the email address is misspelled. 

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