Sending solicited mass email

Question

Our company does work environment surveys, and these surveys are filled in online. All participants are sent a link to their survey in an email (personal code included).

Answer 1

You need use a third party email provider such as aweber or icontact. For a very reasonable fee these companies will make your email delivery issues go away. You can fuss with headers and white listing servers until you see spots, but you will continue to have problems.

This is something that is worth spending money on.