GrayMail issue with Email Blasts

[Anonymous]

I have recieevd a few fowards from recipients of previous email blasts that show the subject line contains the word [GRAYMAIL]. I understand that GrayMail is a form of solicited bulk email messages that don't fit the definition of typical email spam. It is only happening with a few people. How can we stop this from happening?

[Josh_Hill13]

As with all emails, send targeted emails with clear CTAs that people want.
http://blog.hubspot.com/marketing/what-is-graymail-ht

So it would seem your emails aren't being engaged with and their server is starting to block you.

http://thenextweb.com/lifehacks/2014/08/05/minimize-spam/