Here is the perfect way to start an email - and 20 greetings you should usually avoid

This one sounds abrupt.

Again, if you're writing to a group, use "Hi, everyone."

Don't take it upon yourself to call William "Will" or Jennifer "Jen." Unless the person has introduced themselves using a nickname or uses one in the signature of their own emails, stick to their full name.

It's sexist, Pachter says. If you're addressing a group of people, say, "Hi, everyone."

Spell the recipient's name correctly!

"Many people are insulted if their name is misspelled," says Pachter. "Check for the correct spelling in the person's signature block. You can also check the 'To' line. Often, people's first or last names are in their addresses."

Do we really need to explain why this one is a no-no?

First off, it's a bit informal and abrupt. Then when you tack on the exclamation point, it just gets annoying.

"It's a bit jarring right off the bat — like someone is shouting at me," Schwalbe says. "Even without the exclamation, it's a bit abrupt. Better to precede the name with 'Hi' than just blurt it out."

Pachter says that this is how young children address their teachers: "Mrs. Susan, can you help me with this math problem?"

It's not appropriate in the professional world.

Another stiff and abrupt one. The recipient may feel like you're about to reprimand them.

It may not be morning, afternoon, or evening anymore by the time your email reaches the person — or if they're in a different time zone — so it's best just to skip these.

Not bad, but a bit informal if you're addressing someone you don't know very well.

Way too formal!

Plus, this salutation tells the recipient that you have no idea who they are, says Pachter. "Why then should the reader be interested in what you have to say?"

Schwalbe adds: "This one is very stiff. It always feels like bad news or a complaint will follow."

Apart from being generic and giving off an impersonal vibe, this one can be offensive to the recipient. As one informal New York Times poll found, few women really appreciate being called "ma'am" — it tends to make them feel old and disrespected.

Granted, addressing your email to the position your recipient is better than going with 'To whom it may concern, ...' — it shows that you put in some effort.

But it still reads as extremely generic. And if you're already putting in effort to figure out what the position of the person you're addressing is, you'd be better off going the extra step and figuring out who that person is. All it takes is a little more sleuthing.

"If you don't know my name, or can't be bothered to use it, we probably aren't friends," says Schwalbe.

Again, it's not the worst greeting in the world, but it's a little old-fashioned.

The "Dear" family is tricky because it's not always terrible or wrong to use, but it can sometimes come off as a bit too formal.

The recipient might think, "OK, this doesn’t concern me ... I don't need to continue reading."

It's also a cold and very impersonal way to start an email message.

This is a good backup to "Hi, [name] ..." if you don't know the recipient's name. But you should always do whatever you can to find out that information.

This is fine to use with your friends, but the very informal salutation should stay out of the workplace. It's not professional — especially if you're writing to someone you've never met, says Pachter.

Schwalbe agrees: "I can never get out of my head my grandmother's admonition 'Hey is for horses.'"

Also avoid "Hey there." It tells the person, "I don't know your name, but if I try to sound cool and casual, maybe you won't notice."

If you want to make it a little more formal, you can always use the person's last name: "Hi Mrs. Smith, ..."

"The reason I like this one is that it's perfectly friendly and innocuous," says Schwalbe.

It's also Pachter's favorite. She says it's a safe and familiar way to address someone, whether you know them or not.

So when in doubt, go with "Hi."