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Add a human-readable name to email "From" addresses
EX: From:Rachel's Photo <service@rachelsphoto.com>
The email will appear in a customer's inbox as "Rachel's Photo" rather than "service@rachelsphoto.com".
Not having a "real name" is also one of the tests which makes a message more likely to be identified as spam (known as the "NO_REAL_NAME" test).Include the order number in the subject
Include his store address in the email body
Avoid using All CAPs and stick to proper grammar conventions
These additions/changes to the email message content can help lower its spam score when analyzed. There are several websites and services that will rate what you've got and help with this effort.Use the Samples provided and edit them to make them yours. Samples can be found Here