We're having difficulty with some of the Canadian ISPs marking our content as spam. We have gone over the guidelines provided by SendGrid and have implemented everything. The mail itself is single-shot messages from our customers to their customers and isn't mass mailing.
The one clue we have is that the receive from header is being marked as not recognized as the sender. The receive from for SendGrid is fine and has DKIM against it and is marked as valid. The originating system receive from that is for the system that talks to the SendGrid relay is what is causing the problem. This seems like it should be a common problem as we're not doing anything different.
We attempted to use the SendGrid API instead of the relay and we're still seeing that original header. When we send the same note from the SendGrid lab (i.e. not from our originating machine) it doesn't end up in the spam folder. We also attempted to set a SPF record on the originating machine, but the same problem still occurs.
Anyone else have this kind of problem? Any way of hiding that first receive from? Any other suggestions to help? Any hints would be greatly appreciated.