The vast majority of email messages floating around the Internet is still junk messages that qualify as spam. Because of this, there are layers of spam filters that every message you send is subjected to and when you innocently use a specific word, phrase or image it's possible that you message looks like spam. These filters use a scoring system that isn't the same as a human reviewing your messages, which will determine the fate of every message you send. There are many keywords that you should avoid, but without some help, you won't know what those words may be unless you use the free tool atand#160;https://www.mail-tester.com It's a simple testing process that will provide technical feedback on any message that you send to the generated email address on the screen. When someone tells you that they haven't gotten your message, you can do a quick test to see if it might have been flagged as spam using Mail Tester. The results can help you quickly understand any mistakes you may be making especially when sending lengthy messages.