Delivery Status Notification (Failure) - Message Not Delivered

The response from the remote server was:
554 5.7.1 [P4] Message blocked due to spam content in the message.

When I use EM Client to send an email to an address (older CenturyLink account) I get back a ‘Delivery Status Notification (Failure)’. When I try to replicate using  my email provider’s web client (Gmail) the Failure does not occur. As a workaround, the embarqmail user I am sending email to is able to whitelist my gmail account in their Spam filter, allowing EM Client to successfully send the email, but this is obviously not a solution… Any suggestions? Thanks.

It could be that if you are using a signature on your outgoing email, the server thinks that is spam content. It is not that unusual, and the solution is to either remove the signature, alter it in some way, or to put the signature in a template instead.

Well, I double checked the settings to be sure, but my emails contain no mail templates or signatures. The “Attach signature to emails from external applications” box IS checked, but that was an EM Client default setting… 

Also, the only things in the email were the word “Test” in the subject and “test” in the body…

An email with just those two words could quite easily be considered spam.

If you ask the recipient to remove you from their whitelist, and then send a normal email and see if it works.

Well, I had the same thought, so I tried:

Subject: Another Attempt
Body: Let’s see what happens…

But the issue remains, that when I send these same exact messages from Gmail’s Web Client instead of EM Client, the Delivery Failure does not occur…

What is the domain to which you are sending?  (Registered to CenturyLink)

Sorry, you did say before. Of course this doesn’t make sense that whitelisting differentiates by email client, so there must be something else going on there.

I wonder if your recipient could ask their support about this.

I agree… and I’ve scoured the settings in each of the clients to no avail. I will suggest that he contact his support and see if they come back with anything. If so, I’ll be sure to post their answer.

Either way, I appreciate your thoughts. If you can think of anything else (or if anyone else reads this and has any thoughts),  please let me know. Any and all suggestions are welcome!