Email has become my number one enemy lately. It is sure tough to ensure the quality receipt of emails when your are doing large email blasts.
You have to start at the DNS and Server Configuration and make sure your domain email records are setup correctly to reflect your email send / receipt infrastructure.
You have to make sure your server is configured correctly and IP Address, naming ,etc is all in sync with your DNS records.
Then we start talking content, what content is going to trigger SPAM filters. I found a decent tool for doing this at: http://www.mailingcheck.com/download-spam-checker/
This helps to see if your content is considered SPAM and give an appropriate scoring to determine this.
Then with all this configured and setup properly you will still deal with other issues...each server receiving emails are going to interpret things differently. Sometimes we send too many emails in one day to a particular server such as sap, ibm or microsoft. Then they start bouncing.
Then we just deal with some messages never being received at all. So where did they go? What happened.
Then you deal with different receivers within an organization interpretting differently and having really tight SPAM filters on their client or reporting you as SPAM and getting you blacklisted.
Ohhhhh the fun never continues. More to come on this.