Email Error 421 InMotion Hosting ContributorUpdated on August 16, 2021 2 Minute Read A 421 email error is typically a temporary routing issue on the receiving mail server’s end. These should usually be resolved automatically, and you should receive a final bounce-back message if the message completely fails. You usually would not receive a bounce-back message for this type of error. If your message is going to be delayed more than 24 hours, then sometimes a “delivery has been delayed” soft bounce will be returned to you, to let you know that the delivery has yet to complete succesfully. Common variations of the 421 email error 421 4.2.1 : (DYN:T1) https://postmaster.info.aol.com/errors/421dynt1.html 421 4.3.1 Out of disk space for temp file 421 4.3.2 All server ports are busy 421 4.3.2 All server ports are busy 421 4.4.2 mx.aol.com Error: timeout exceeded 421 #4.4.5 Too many connections from your host. 421 #4.4.5 Too many connections to this host. 421 4.7.0 mx.aol.com Error: too many errors 421 4.7.1 : (DYN:T1) https://postmaster.info.aol.com/errors/421dynt1.html 421 4.7.1 POL-T2 https://postmaster.facebook.com/response_codes?ip=74.124.194.252#pol-t Connection refused 421 4.7.1 POL-T2 https://postmaster.facebook.com/response_codes?ip=74.124.194.252#pol-t Connection refused 421 Downstream server error 421 Fork failed 421 Greylisting enabled, please try later. 421 LDAP verification agent temporarily unavailable: Connection failed 421 mail.RemoteDomain.com out of connection slots 421 mx.aol.com Service unavailable – try again later 421 Service not available – too busy 421 Server busy, try again later – psmtp 421 service temporarily unavailable 421 Temporary error (#4.3.0) 421 Too many concurrent SMTP connections; please try again later. 421 Unexpected failure, please try later Resolving a 421 email error Because errors in the 421 series don’t bounceback right away they would be considered a soft bounce. To better understand soft and hard bounces, and general email bounceback errors you can read why does email bounce, bounceback, or error? Seeing a large amount of 421 email errors in your server’s mail logs could be an indication that a lot of your mail users are having difficulties getting their e-mails delivered out successfully on the first attempt. Share this Article InMotion Hosting Contributor Content Writer InMotion Hosting contributors are highly knowledgeable individuals who create relevant content on new trends and troubleshooting techniques to help you achieve your online goals! More Articles by InMotion Hosting Related Articles Transferring Emails from Your Old Host to InMotion Hosting How to Setup Office 365 DNS Records How to fix OLMAPI32.dll and WWLIB.dll error in Outlook 2013 How to Setup Outlook 2016 for Mac Issues with Outlook 2007 Running on Windows 10 Outlook not working after installing Windows 10 IMAP Issues Affecting Outlook 2013 and Office 365 Outlook 2013/Office 365 – Subscribing to your Inbox How to create an email signature in Outlook 2003 How to create an email signature for Mac in Outlook 2011
