eMails to Comcast.net addresses not being delivered
I serve on the board of my large community organization. We send emails to our 200+ membership using MailChimp. Since December, I have received feedback that emails to sent to numerous comcast.net members are not getting delivered or are being delivered intermittently. The problem seems to arise when the emails are sent from a gmail.com email address. This does not seem to occur when the MailChimp message is sent out under a comcast.net address. In all cases, in MailChimp it shows the messages as being delivered, but I confirmed with users that they did not receive and it is not in their spam folder.
Please advise what measures can be taken to correct this problem.