Thanks for getting back to us,
Yes, that time I also tested Joomla registration page, it did send out those activation email to the new register user.
After debug long hour ago, I suspect your mail server did enable some content filtering feature, so some of the content will treat it as SPAM, this is why your mail server doesn't send out those blog email to the user.
Based on what i tested, if I replace those email content to normal sentence like "this is test post ", it can able to send this email to me , you can check my screenshot here :
http://take.ms/q9EiQ .
So this can able to prove that some where your mail server did filtering the email content before it send.
I did attached a file which contain one of the email content generated from Easyblog, can you pass this to your mail server support and see whether there got any content detect it as SPAM?
If I remove this particular content (screenshot :
http://take.ms/kI6v4), it can able to send out the email. (screenshot :
http://take.ms/A16hB), so I assume that is it your mail server detected if there got any duplicate content in email, then it will not send this email out?
The reason why this email content has duplicate content is use to solve it for the outlook mail client for some specific issue and this duplicate content will not show into the email when the user read it.
And 1 more question, can you consult with your mail server support and see is there a way to temporary disable this content filtering feature? But I am not sure is this the correct term i mention this feature.
By the way, keep us update then.