How to Avoid Gmail / Yahoo from including "This message seems dangerous"?

We suggest using Standard template provided by Markate. if you prefer to use Custom Email Template

There are a number of things you can try to help prevent your emails being seen as potentially dangerous:

• Do not use CSS or HTML to hide content within your messages.
• Do not Copy Paste message from other web pages.
• Don’t embed lots of images. 
• Check for and fix any broken links. And don’t include links that run multiple redirections.
• Avoid adding lots of recipients.
• Keep links in the email body and signature to a minimum.
• Avoid attaching a lot of files. 
• Ensure the email is well written and don’t use too many spam trigger words.
• Avoid having the same email address in the From and To fields.