What is the correct way to write to whom it may concern?

The correct way to write To Whom It May Concern is to capitalize the first letter of each word. Be sure to always use 'whom' instead of 'who' or 'whomever'.

It's also more appropriate to follow the phrase with a colon rather than a comma and add two spaces before beginning your message. Using this phrase suggests a formal letter and should only be used when you're sending something to an unknown recipient.