How to prevent my email from going to the spam/junk folder

Email deliverability can be an issue that plagues even the best infrastructures. Even if the email gets successfully sent, it's still at the mercy of the receiving end and could be blocked/filtered as soon as it reaches the user's mailbox, or even before it does.

Ultimately, mailbox services like Gmail will never disclose their exact algorithms for what identifies an email as spam which makes sense considering how actual spammers may take advantage of such information.

Follow Best Practices

If you look it up online (like from this help doc from Google themselves), you'll be told that there are a number of factors that may cause this to happen, but there is not a known exact set of causes nor solutions - only suggestions that may help with improving your email deliverability.

Here are some examples:

• Customize your project's default emails. Since all created projects/campaigns start with the same template email content (subject line, body content, email layout used), we highly recommend that you should always update and personalize your email messages to match your unique brand and voice. 
• Always have an Unsubscribe link - While an unsubscribe link must be included in every email sent through Prefinery (all default email layouts have them in the footer), we also recommend that it be simple and easy for your recipients to find.
• Avoid URL shortening services to add links within your emails - Since URL shorteners are used by spammers, the URL or source IP address of the services are frequently added to block lists. Always try to use your own domain or the url of a service you know is not used by spammers.
• Don't mismatch URLs - As much as possible, ensure the URLs of your image sources and link URLs in your message match the FROM/sender email address domain you're using. Most email services recognize image assets hosted on CDNs (Content Delivery Networks) and hosted links (e.g. unsubscribe link) of email service providers so they're an exception.
• Links in the body messages should be visible and easy to understand - Recipients should know where they go when they click links.
• Subject lines should be relevant and not misleading - If your subject line makes your email look like spam, then people and the spam filters that ISPs put in place to protect them will probably think that it’s spam.
• Don't use too many images (nor use only images) in the content - Emails with very little text copy and many images, or simply composed of one large image, are popular with spammers.
• Avoid sending mails to the same user in bursts - If you've setup multiple emails to have the same trigger, add varying/incremental delivery delays to each as to not bombard the user with multiple emails in a very short period of time.
• Don't send the same exact email at the same time - Receiving multiple copies of the same exact email at once or within a few seconds from an unknown contact can trigger spam filters. Use delivery delays as previously mentioned, as well as email personalization variables to make each email different, even if it's by the same email message (e.g. for reward or "referral earned" emails).

Review Email Activities Outside of Prefinery

Your email sending reputation outside of Prefinery can also be carried into your Prefinery emails. In other words, your emails can be automatically flagged as spam or junk based on your sender address domain's email practices as a whole, not just based on the particular email being sent nor just by being sent through Prefinery.

For instance, if you are using both MailChimp and Prefinery, and over at MailChimp you've been sending marketing email that looks a lot like promotional or spam stuff Gmail may learn that all sending from yourdomain.com is spammy and so flag a seemingly innocent "Thank you for joining the referral campaign" email from Prefinery as spam.

Do a review of your email activities outside Prefinery and ensure that your sender address domain hasn't been used nor currently being used to send overly promotional, seemingly spammy, or spam-like content.