If you send Emails - You might like this

Complexity aside, there is a very simple and efficient way to improve your sending score.

Whether you are sending emails with your own server/IP, or relying on an email delivery service like Mailgun, you should always check the validity of the email address before sending an email.

This is for a variety of reasons; mainly, it affects your score.
I have posted a simple Expect script on Github to help validate an email list.

The concept is simple, send a "helo" to standard port 25 on one of the SMTP servers you want to send the email to, then verify the recipient.

Checkout my Github link for a simple proof of concept
https://github.com/jacopovalanzano/expect-email-fetch