Delivery to the following recipients failed permanently

... Reason: Permanent Error

If you do "View Source" on that bounce message you may find additional information in attachments below the message body. (Hard to believe the Forum security bot zapped the Comcast "mailer-daemon" address. Not like it's a secret! {Sigh!})

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

Hello @user_50a3bd, thanks for reaching out for help with your email and to share your experience. It's definitely strange to hear that you are having trouble sending an email to one recipient, but we have a team that can help. Our CSA (Customer Security Assurance) Team can look at this in more detail and should be able to provide you a reason as to why the delivery is failing. 

This team can be contacted at 1-888-565-4329, 8:00am - 12:00am EST, 7 days a week. 

Typically when this happens, it's something on the receivers end preventing the email form going through, but our CSA team should be able to determine the exact cause. 

@user_50a3bd it looks like your first message to alseib.org (if that's the message you're talking about) failed, though the second went through.  The first message failed due to a message size limit imposed by the receiving system.