How to Prevent My Email Messages From Going to Recipient Spam Folder
Spam is a nuisance and a drain on both time and resources. Most email programs are set up to filter, block and destroy spam without the recipient ever reading or seeing the message. This is useful when messages are truly spam, but when you have a message to get across, it is important to make sure your work does not end up in someone's spam filter.
Include plain text in your email. Emails that are entirely HTML or that include just images and links are a flag for spam, particularly if those links have become blacklisted at some point. Personal emails contain plain text, so including this text will tell spam filters that you are a real person, not a spammer.
Avoid too many attachments. One of the dangers of spam is they can contain virulent attachments; uploading and hosting images and creating links instead of attachments will not only avoid spam rules, it will also help your emails to load faster.
Avoid using phrases that can trigger spam filters. Many spam filters function by text alone and a high density of "risky" keywords means that your mail will be caught and flagged as spam. There are websites that keep current lists of spam keywords (see the Resources of this article) and making sure you are up to date on the latest spam content will help you to avoid it.
Use SMTP sending instead of direct sending. Many spam filters will carefully scrutinize directly sent emails with long headers and lists of recipients. Using Simple Mail Transfer Protocol (SMTP) will allow you to email many recipients without triggering this function.