Need to email someone but don't have their address? Whether you're a disgruntled customer looking to lodge a complaint with someone in charge, a reporter trying to get in touch with the right person, or just attempting to get in touch with a long-lost friend, you may not have the recipient's email id.

We have told you how to verify if an email address exists, but to find one you don't know requires a little ingenuity.

Guy has previously suggested a few ways to find someone's email address, but I have some more solutions. All you need is a Gmail account and some common sense to come up with solutions that will help you figure out most people's true email addresses. It's not easy, but desperate times can call for desperate measures.

Google Your Recipient

The first and easiest step is to do a Web search for the person you are wishing to get in touch with. If it's a friend, you know what they look like, but if it's someone else, you can always find a photo of them somewhere on the Internet. And if it's on the Internet, it's on Google Images.

Scour through the images and find out what that person looks like. This is an important step because you are going to need it to verify if it's the right guy. Indeed, there are plenty of websites to help you find people on the Internet.

Also, try to get any other information about that person, such as where he or she works, their location, and so on.

Permutations & Combinations

For the sake of example, let's say you want to find the email address of Matias Duarte. Now, you know Matias Duarte works at Google, lives in USA, and you have an idea of what he looks like if you have Googled him. And just in case it's not a photo of him, you can even come across what he uses as a profile pic on different social networks.

So take all this info and make a list of the possible different email addresses he might have, such as:

matiasduarte@gmail.com

matias@gmail.com

matiasd@gmail.com

mduarte@gmail.com

matiasduarte@google.com

matias@google.com

Test your imagination and really make as comprehensive a list as possible.

Head To Hangouts

Gmail's new Hangouts feature is closely tied into Google+, using the same Gmail address for both. And you can make that work to your advantage.

First, in your Gmail, you need to change your Google Talk chat window to Hangouts if you haven't already done that. Click the drop-down arrow for Options next to your profile pic and choose "Try The New Hangouts". Your page will refresh and instead of GTalk, you will have Hangouts.

In the search box of Hangouts -- where it says "Name, email, number" -- type the email address guesses you had come up with, one by one. Every time you type a valid email address, Hangouts will show you a tick mark with a profile pic, indicating this is a proper email. With the pic, you should be able to tell whether that's the person you want to mail or not.

An email address that shows ‘Unnamed' and no profile pic is a dead-end you should avoid, whether there's a tick mark or not.

I've used this technique several times to get in touch with people for articles or even to cold-call senior execs. It's efficient and it has the added advantage of often getting the personal email id of whoever you are trying to reach, making it that much more likely they will read the message.

Root Out With Rapportive

This isn't a trick I have used before, but Labnol.org has a similar hack that uses the Gmail extension Rapportive.

Install Rapportive, connect your social accounts to it, and then open a new Compose window. Just like with the Hangouts hack, now paste the different email address permutations and combinations in the ‘To' field.

Rapportive will scan the addresses and give you information on the people in it. You can hover or click on any id to see its info and narrow down your search to the right person -- and just like that, you have their email address.

This hack is especially useful since it doesn't restrict you to email addresses that use Gmail or Google Apps, which Hangouts does. That said, you aren't always going to find the personal id of a person, and chances are that your email to a specific work id won't even be checked, or could be trashed without opening.

Use It Responsibly

Now, this hack can possibly invade someone's privacy, so we implore you not to use it irresponsibly. It's one of those times when Uncle Ben's wise words to Spidey should be ringing in your ears: "With great power comes great responsibility."

Being on the wrong end of this hack can be bothersome, so remember our tips to protect yourself from spammers and hackers.

Still, this is a great way to get in touch with the right person when there seems to be no other way to do that.

Do you have your own tricks to find someone's email address? We would love to know, so please share in the comments.