Best practices for boosting email deliverability rates

As a mail sender, your reputation is quite crucial. Deliverability of mail is much more important than the content you are sending. Email deliverability can make or break your reputation.
“The most important fact about email is that 21% of opt-in emails never make it to the inbox.”
For example, if you have a list of one million subscribers and 21% of your emails to those recipients go undelivered, then 210,000 people were left waiting for your email that never arrived.