Even the most well-written message will do you no good if it never arrives in your affiliate’s e-mail inbox.
Make sure your welcome letters and other messages don’t fall prey to the various spam filters used by all e-mail hosts. These filters typically identify words (especially if used repeatedly in an e-mail) they deem likely used in spam.
Fortunately, there are numerous free online tools you can use to help ensure your messages don’t get flagged as spam and are NOT delivered to your recipient’s inbox as intended.
I recommend you check each of your messages using two or more of these checkers:
Lyris Content Checker
Melon Stork Email Deliverability Spam Checker