Mail sent from AWS going to spam

I'm running a number of wordpress sites on an AWS EC2 instance.

One of the sites is using WooCommerce for an online shop. when an order is made a confirmation email is sent out but these mails all seem to go straight to recipients' spam.

The client has their mail hosted with outlook.com.

what would be the best solution for safely sending out mail when MX records etc are all hosted elsewhere?

thanks

Firstly, check if you own the IP mail is coming from or if it is shared. If you own it, you can do all of the below: If it's shared, you're unable to consider the bottom ones.

Consider the content of the messages. E.G avoid image heavy messages or well-known words/phrases that trigger junk filters.

Avoid sending to large number of recipients in a single messages.

Check the addresses you send mail to. do they all want to receive your message?

Add SPF records to clarify which sources can send from @yourdomain.com check your server isnt insecure etc (tolls like https://mxtoolbox.com/diagnostic.aspx are great for this)

check your IP(s) aren't on email blacklists.

Apply rDNS records to verify your IP is yours.