The issue of the hyphen (or lack thereof) in email is still far from being settled. Even though it seems that most of the world has moved on and settled on the simpler and newer variant of spelling—email—there are still giants like Merriam-Webster, The Chicago Manual of Style, and the New Yorker that are sticking with the older way of spelling email.
And they might have a point. Email is a compound noun, made out of two words—“electronic” and “mail.” As far as names go, this one describes its subject pretty accurately—email is like mail that you send electronically. The e in email is the abbreviation for “electronic,” and it’s used in a lot of other words as well—e-commerce, e-learning, and e-business, for example. There are also other compound nouns which are formed from an abbreviation and a noun, like the H-bomb, which is short for hydrogen bomb. The general rule of hyphenation in compound words that contain a single letter (or a number) and a word is to hyphenate them. So, based on tradition, e-mail is the correct way to do it. But there’s a “but.”
In the case of email, it can be argued that the widespread use of the unhyphenated spelling has made this compound noun an exception to the rule. It might also be said that closed (unhyphenated) spelling is influencing the way we write other compound words that follow the same model, but good luck with arguing that “tshirt” is a good way to write “t-shirt.” Whatever way you want to approach it, “email” is the variant that’s being accepted or recommended by an increasing number of publications. Arguably the biggest blow to the pro-hyphenation camp came in 2011, when The AP Stylebook came down on the side of email. In 2013, the New York Times joined the anti-hyphenation ranks, also filled with media outlets like the Guardian and the Huffington Post.
So where does this leave you? Which one should you use—the stubbornly traditional e-mail or the popular and generally accepted email? Unless you have to adhere to a style guide, it’s completely up to you.
Examples of “e-mail” in publications:
“The French government has taken a bold step to limit time spent looking at work e-mails by giving employees the right to disconnect.”
—Globe and Mail
“Clinton has made plenty of bad moves with regard to her e-mail server.”
—The New Yorker
“Setting up your own blockchain-based assets and trading network may become just as simple as signing up for an e-mail account, according to a Hong Kong-based financial technology company.”
“A ‘mistake’ is when one hits ‘reply all,’ and dozens or hundreds of people unwittingly receive a sensitive e-mail meant for one person.”
—The New York Post
Examples of “email”:
“Productivity is all about the strategy, and so installing specialized email apps can help you accomplish a lot.”
—The Huffington Post
“The data may be eight years old, but with around 360 million accounts, there are sure to be some people still using the same email address and password.”
“Oracle’s attorneys discovered two emails that suggest Google knew full well the APIs were copyrighted.”
“In an email to Poynter, a New York Times spokesperson said the newspaper is not aiming to cut an exact number of employees or free up a specific amount of money.”
from Grammarly Blog