If you're a working professional in a corporate office, then emails are very important for you because one has to communicate with the client, colleagues and seniors from email addresses only. And it does not look when your sent emails going to trash on the receiver email account. To fix this issue, you need to make sure that you're not doing any of these:
1) Unnecessary link insertion to the wrong website.
2) Using keywords like SALE, Buy now, etc.
3) Entering the recipient's email id is wrong.