Don’t send email directly from your web server
Web servers are normally not optimized to send email so we recommend sending all of your store’s email via a dedicated email service. Email services make sure that your email is being delivered through a reliable source and using one will give you better insight and scalability. There are many services available and most have generous free tiers, here are a few:
More about external SMTP email : Reliable WordPress Email with External SMTP Integration
Make sure your content doesn’t look like spam
The subject and content of your email will also impact the spam score, here are some things to watch out for:
- Avoid phrases that sound gimmicky: Free, As Seen On, Double Your X, Money Making, Get Paid, Make Cash, Pre-Approved, Satisfaction Guaranteed, Low Price, Save Big. You’ve heard these all before.
- Be sure the sender name is relevant to your business or site to prevent confusion.
- DON’T USE ALL CAPS IN YOUR SUBJECT LINE! Spam filters are always on the lookout for this.
- Be careful about the quality and quantity of links in the content and don’t use URL shorteners.
- Give a clear and obvious unsubscribe link from future emails.