Hi!
This is not actually a bid for your project. I'm not sure that the content of your emails is the reason for rejecting. I think I can help you with some guidelines for free. I have some experience with sending emails and SMTP servers. I'm currently working for www.tweewoo.com. We are sending thousands of emails every month (we have more than 20 000 users), and my boss is sending newsletters every 3 days (HTML+images based on our server). Please, think about the following:
1. Do you send emails using a regular smtp email server, based on your hosting server? The email user can be no-reply@[your domain].[com|net|org etc] or news@[your domain].[com|net|org etc] but the email server should be hosted on your domain.
2. You need also to check if your domain is not in the email servers black list. If it is blacklisted somehow, then you need to change the domain of the mailing server in order to avoid the black lists.
3. Do you have DNS Sender Policy Framework (SFP) records? This is really very important, especially for the Google based customers. It is not hard to set up SFP DNS Records but it is extremely important.
We have the following configuration:
1. The secondary MX records of our domain are assigned to our hosting server.
2. We are using an SMTP server, that is installed on our hosting server. This is not the server we use to send our company emails. But this is the server that our newsletter software uses.
3. We have approved SFP records in our DNS.
Regards!
Tsvetan