Errors in HTML tags could send your e-mail into the bulk folder
Mail marketers often believe that any e-mail that has in its subject or body the words “free” would be filtered. But this is not always true. Even though certain mails, which include different combinations of words containing “free” are filtered, the ISPs could often block your e-mails for other well-known reasons.
As a good example one can use the HTML code. If you use in the e-mails you send incorrect or outdated code, domains such as Hotmail and AOL would surely block it, either send to bulk or junk folders. Even if you see

