Common Email Bouncebacks
A bounceback message generates when there is an issue with the sending or receiving mail server. The bounceback error typically gives us some insight into what the problem is. Below is a list of potential bounceback errors and their meanings.
|SMTP 421 (Server Temporarily Not Available)||Temporary fail because our mail queue is too full.|
|SMTP 421 (Temporary Rejection. Reverse DNS for "IP" failed)||SMTP Temporary rejection - Couldn't identify the PTR record.|
|SMTP 452 ("toemail" requested action aborted: try again later - GL/GL)||Temporary failure. The account is using greylisting and will be accepted when the delivery is retried.|
|SMTP 550 ("fromemail" max messages per session)||Too much mail sent at once. Email limits exceeded.|
|SMTP 550 ("fromemail" sender rejected||Email address isn't properly formatted (has no @domain).|
|SMTP 550 ("toemail" recipient rejected GL/BL).||Permanent failure. The sender is blacklisted at the user level (the customer blacklisted them).|
|SMTP 550 ("toemail" recipient rejected)||The "To" mailbox doesn't exist.|
|SMTP 552 (Remote MTA $ip: An URL contained in this message is blacklisted by Spamhaus DBL. See http://www.spamhaus.org/dbl)||A URL in the body is blacklisted|
|SMTP 552 (virus infected message rejected)||Cloudmark detected the message as having a virus|
|SMTP 552 (virus infected message rejected)||Sender attached something a file format that our server does not allow (.bat .btm .cmd .com .cpl .dll .exe .lnk .msi .pif .prf .reg .scr .vbs)|
|SMTP 554 (Connection refused - "IP")||This is rejected for spam based on CSI|
|SMTP 554 (Connection Rejected. Reverse DNS for "IP" does not exist)||Permanent rejection. They don't have a PTR record.|
|Reject connection SMTP 554 (rejected for policy reasons)||Was blacklisted or detected as most likely being spam. The recipient server has doubts about the sender’s authenticity or the sender’s message.|
|Reject SMTP 550 ($toemail recipient rejected - ERR016)||The recipient is blocked for spam, blacklist, email limit purposes.|
|SMTP 452 ("fromemail" sender rejected. Too many messages for this connection ERR034)||Too much mail sent at once. Email limits exceeded.|
|SMTP 550 ("fromemail" sender rejected - ERR082)||The sender is blocked for spam, blacklist, email limit purposes.|
|SMTP 550 ("fromemail" sender rejected - ERR081)||Domain is blacklisted.|
|SMTP 550 ("fromemail" suspect invalid mailer domain please check your dns records - ERR006)||The 'From' email is sent as an IP address.|
|SMTP 550 ("fromemail" Suspect invalid mailer domain please check your DNS records - ERR007)||No A or MX records.|
|SMTP 550 ("fromemail" Suspect invalid mailer domain please check your DNS records - ERR008)||
|SMTP 550 ("fromemail" Suspect invalid mailer domain please check your DNS records - ERR009)||Invalid A or MX record.|
|SMTP 550 ($toemail recipient is invalid - ERR010)||The 'To' email is an IP address.|
|SMTP 550 ($toemail recipient is invalid - ERR011)||Recipient DNS check fails.|
|SMTP 550 ($toemail Recipient is invalid - ERR013)||The recipient domain is not FQDN.|
|SMTP 550 ($toemail recipient is invalid - ERR014)||The email recipient is not a valid email address/domain.|
|Reported error: 550 The Domain Name System (DNS) reported that the recipient's domain does not exist||
Basic Troubleshooting Guide
- Check the existing Inbound Filtering policies that the email may have violated.
- Check if the email address is in the Blacklist and if the sender can be trusted, add it to the Approved Senders list. Please note that this option is not yet available in the Foundation dashboard.
- Make sure that the recipient of the email you are sending is valid.
- Check the IP address of your mail server to see if the receiving domain is blocking it.
- Contact the receiving domain and see if they have any policy restrictions or blacklists that may be causing the bounced emails.
Troubleshooting Common Email Issues
I Can't Send Email
I Can't Receive Emails