General best practices to help the content of your emails from being spammy.
What you shouldn't do:
Avoid having an excessive number of links
Avoid lots of large images, or compress the images before inserting them
Some spam filters are looking for keywords like "promo" "sale" "urgent" "amazing" "promise" "special" "free" "guarantee," no obligation," and so on.
Don't use all caps anywhere in your email or its subject line.
What you should do:
Include an Unsubscribe option
Look through your own spam mailbox to see what your emails are automatically flagging as well. That can help you think of words or phrases to avoid as well.
Include your recipient’s name in the subject line via Email Tags
Test your emails before sending them. Each email clients displays emails differently ie Outlook, Gmail, Apple iPhone's Mail, etc.
Finally, don't forget it is important to set up your domain's DNS settings to authenticate Loxo's domain. This is an important step if you are planning on sending large bulk emails from Loxo.