Email marked as FAILED has hard bounced but I know the email address is correct - what can I do?  


Valid email addresses can hard bounce for different reasons, please keep reading to find out why a valid email address can hard bounce and what can be done. 


Valid email addresses can hard bounce due to: 

1. Emails blocked by a firewall or spam filter


If your email was blocked, this may be due to a spam filter having found your email contained spam content.  


Spam filters can be on the recipients computer, on their company's email firewall, at their ISP/Data centre, or all of the above. 

Common SMTP replies for spam filtered emails include Denied, Unacceptable Content, Blocked, and similar messages.

2. Block on email server 


Corporate spam filters and email firewalls can be very strict and treat a large amount of identical incoming emails as spam. If the spam filter or firewall is used to seeing you send one or two personal emails to a client in the company, they may interpret a bulk send made on your behalf as spam.

A block can be temporary if the recipient email server thinks too much email is coming from one server too fast. Other times the block is permanent and the only way to get around that is to ask the IT group in charge to white-list your email address. 

3. Internet Service Provider (ISP) blocking your emails

In the case of bounces to a large number of email addresses at the same domain - it may indicate that your emails are being blocked by the Internet Service Providers (ISPs) receiving server, such as email to Yahoo, Hotmail or Gmail accounts. 


ISPs and other mail systems check incoming mail from each source and can see if you are sending to a lot of addresses that are bouncing. 


If they detect that you are then they will start rejecting your campaigns on the assumption your list is made up of automatically generated or purchased emails. 


In other words, they may be blocking you on the assumption that you are a spammer.  Our advice would be to contact the ISP that handles this mail to ask them to unblock you as a sender of email. 


You may need to set up SPF/DKIM records in order to make sure your email is received, if they ask for this please our Support Desk so that we can provide you with these details from our email platform. 

4. Is the IP address of your email server listed on a blacklist? 

The recipients email server may also look at the IP addresses of the email server that the email is coming from - if the IP address is found on a blacklists then this can be why the recipients email server rejects the email and so it is blocked. 


If your mail servers IP address is listed on a blacklist you will need to get in touch with the list to request your IP address be removed.