How can I get my email on more than one computer? (6/30/11)

The problem
You've been sending and receiving email using your computer for quite some time now. Recently you got a second computer, which you may simply use elsewhere in your home or office, or when you travel. Wherever you may be, it would be useful if you could also get your email on this second computer. This is not difficult to arrange, but first it's important to understand a little about how email works "behind the scenes."

Background
Having an email account is very similar to having a P.O. Box at the Post Office. When I mail a letter to you, it eventually arrives in your P.O. Box and waits for you to go there to get it, along with any other mail that's collected in your box. Similarly, when I send you an email, it doesn't go directly to your computer. Instead it eventually arrives in your mailbox on your email server, where it waits for your computer to get it, along with any other messages that may have arrived in your mailbox.

Your email server is your "virtual post office," and it stores your mailbox on computers that belong to your email service. Companies like Comcast, AOL, Gmail, Yahoo, Verizon, Godaddy and others all have email servers for their email customers.

However, unlike the Post Office, which expects you to empty out your P.O. Box every time you visit, when your computer gets your email you can choose to:

Have it Remove your messages from the mailbox on the server (the typical behavior), or
Have it Leave copies of your messages on the server.

Let's define some terms
In order to succinctly describe the different ways you can get your email on more than one computer, let's say that:

Computer A is the older computer you've been using to get your email, and which you'll continue to use for your email going forward.
Computer B is the newer computer on which you will start getting your email as well.

Typically there are two ways you can use a computer to access your email:

You can use "email client software" on your computer to manage your email. Common email programs include Outlook Express, Windows Mail, Outlook, Thunderbird, and Eudora on Windows, and Apple Mail, Thunderbird, Eudora, and Entourage on Macintosh.
You can use "webmail" (web-based email) to access your email account using your email server's web page. Common email websites include www.gmail.com for a Gmail account, www.comcast.net for Comcast, www.verizon.net for Verizon, www.aol.com for AOL, etc. In this case you would use a web browser (or special software like America Online or AOL Desktop) to access your email account via the internet. Common web browsers include Internet Explorer, Firefox, and Google Chrome on Windows, and Safari, Firefox, and Chrome on Macintosh.

Email client software can typically use two different email protocols to talk to your email server:

POP (Post Office Protocol): A common and simple method of retrieving messages from an email server which, when finished, can then either Remove the messages from the server or Leave copies on the server.
IMAP (Internet Message Access Protocol): A more sophisticated method that gives your email software many of the advantages of webmail, including direct access to your messages on the server. Some email servers include IMAP for free (e.g., AOL and Gmail), others charge extra for it (e.g., Godaddy), and others don't implement it at all (e.g., Comcast and Verizon).

Note that both of these protocols are about accessing your messages, not your Address Book.

Situation #1: If you use webmail on Computer A, just do the same on Computer B
If you're already using webmail on Computer A, you can simply access your email from Computer B in exactly the same way.

Pros:

Since webmail stores your messages and your Address Book on the email server (not on your computer), just start using your webmail on Computer B and you'll have full access to your email with minimal effort.

Cons:

If you have documents on Computer A's hard drive that you might want to attach and send out via email but at the moment you're in front of Computer B, then you won't have access to them without some extra preparation, such as copying those documents to a traveling disk, or emailing them to yourself, or using a service like DropBox (see "A Tale of Two Computers" http://www.kadansky.com/files/newsletters/2009_07_15.html), etc.

Situation #2: You use AOL on Computer A, just do the same on Computer B
If you use the AOL software on Computer A, you can simply install AOL on Computer B.

Pros:

Just like webmail, AOL stores your messages and your Address Book on the email server (not on your computer), so just start using AOL on Computer B and you'll have full access to your email with minimal effort.

Cons:

If you've signed into your AOL account using the AOL software on one computer, then sign in using the AOL software on another, AOL will sign you out of the first computer.
If you have documents on Computer A's hard drive that you might want to attach and send out via email but at the moment you're in front of Computer B, then you won't have access to them without some extra preparation (see suggestions, above).

Situation #3: You use Computer A frequently (with email client software) but Computer B only occasionally
I have many clients who use their "primary" computer every day, and their "secondary" computer (typically a laptop or netbook) only when they travel. In this situation, I recommend setting up the computers as follows:

Computer A: Set email client software to use POP protocol and Remove messages from server (default behavior)
Computer B: Set email client software to use POP protocol and Leave messages on server; as an alternative, use webmail on Computer B

Pros:

Simple, easy to set up
Computer A will get all incoming messages (and "clean off" the server in the process).
Computer B will only get incoming messages that Computer A has not seen yet.

Cons:

When you first start using Computer B for your email, it won't have any previous messages you've sent or received, nor your email Address Book, unless you copy them over from Computer A.
Any messages you send from one computer won't be recorded in the other computer's Sent Items, unless you "CC yourself" (and move those messages from Inbox to Sent Items).
Any messages you delete from one computer won't be deleted from the other computer.

Situation #4: You use both computers frequently (with email client software), and your email account supports IMAP
In this situation, I recommend setting up the computers as follows:

Computer A: Set email client software to use IMAP protocol
Computer B: Set email client software to use IMAP protocol

Pros:

Simple, easy to set up
Both computers will see all incoming and sent messages.
Messages you delete with one computer are removed from the server, so they'll disappear from the other computer as well.

Cons:

When you first start using Computer B for your email, it won't have your email Address Book, unless you copy it over from Computer A.
IMAP isn't perfect. Your email client software may "churn" periodically talking to your email server over IMAP.

Situation #5: You use both computers frequently (with email client software), and your email account does not support IMAP
This is a tricky situation. If you really want both computers to receive the same incoming messages, then unlike Situation #3 above, both computers will have to leave all messages on the server. Since the storage space on the server is finite, eventually the server will "fill up" and refuse to accept any more incoming email. This may take days or it may take years, it will depend upon the number of megabytes of email you receive over time. The only way to resolve this conflict is for you to periodically "clean out" the server manually. If you're willing to do that, then I recommend setting up the computers as follows:

Computer A: Set email client software to use POP protocol and Leave messages on server
Computer B: Set email client software to use POP protocol and Leave messages on server; as an alternative, use webmail on Computer B

Pros:

Simple, easy to set up.
Both computers will get all incoming messages.

Cons:

Since neither computer is removing messages from the server, it will eventually "fill up." You will need to periodically "clean out" the server. You can use the server's webmail (i.e., after downloading all recent email on both computers, quickly sign into your email account using a web browser, select all messages, and delete them), or some email client programs have a built-in function to do this.
When you first start using Computer B for your email, it won't have any previous messages you've sent or received, nor your email Address Book, unless you copy them over from Computer A.
Any messages you send from one computer won't be recorded in the other computer's Sent Items, unless you "CC yourself" (and move those messages from Inbox to Sent Items).
Any messages you delete from one computer won't be deleted from the other computer.

Situation #6: You don't want to copy anything from Computer A to Computer B
Here's a completely different solution to this problem: Rather than setting up access to your email on Computer B and trying to coordinate that with Computer A, instead you could set up "remote access" software so that when you're sitting at Computer B you can "reach over the internet and connect" to Computer A, and then operate it from afar. With this approach you will either:

Use Computer A to operate your email as you have always done, or
Use Computer B to "remotely control" Computer A, and then operate your email on Computer A as you have always done.

There are a number of remote-access services and software packages you can use to do this, including LogMeIn, GoToMyPC, TeamViewer, VNC, and others. In most cases you would:

Sign up for the service,
Create some passwords to control access to Computer A, and
Install some software on Computer A.
Then as needed, using Computer B you'd sign into the service and then access Computer A.

Pros:

These remote-control services are not that difficult to set up, and some are free or very reasonably priced.
You won't need to use any email software or webmail on Computer B.
There's no need to copy your Address Book nor any documents to Computer B.
Computer A remains the only computer accessing your email, so there's no need to coordinate email settings across multiple computers.
Computer A remains your central "base of operations."

Cons:

Remote-control software can be a little confusing to use. You can forget that you're operating "from a distance."
Computer A must be powered on, not sleeping or hibernating, and be connected to the internet for Computer B to access it.
If someone else is using Computer A when you "reach over" from Computer B, they may be surprised when you "take control" of Computer A.
When you're sitting at Computer B remotely controlling Computer A, music and video (including YouTube clips) may be silent, may not play smoothly, or may not work at all. Also, anything you Print will probably come out of Computer A's printer, not Computer B's.

What if I also want to access my email using someone else's computer, not one that I own?
If you're using someone else's computer, perhaps at a hotel or conference center, and you want to check your email, my advice is to use webmail, not email client software. It's simpler, doesn't require much set-up, and doesn't leave as much behind on their computer.

Also, to protect the security of your email account on someone else's computer:

When signing into your email using webmail, always choose No if the computer asks to remember your password.
When you're done, don't just close the email window! Be sure to "Log out" or "Sign out" first, then close the window. If possible, also empty the browser cache (or "temporary internet files").

What if I also want to access my email from my cell phone, smartphone, iPad, or other device?
As long as the device is configured to cooperate with your computer (i.e., it either uses the POP protocol with "Leave messages on server," or it uses the IMAP protocol), then the two machines should work well together. Luckily, this seems to be the current default for such devices.

What if I have more than one email account?
The entire discussion above concentrates on a single email account. If you have more than one, I recommend repeating this analysis for each account.

Conclusions

You can get your email on multiple computers and devices, but it's important to look at the big picture, think about what's important to you, find out what your options are, and then coordinate the various settings.
There is no single solution that fits every person's needs.

Where to go from here

To do any of this you will need your email address and email account password. (All email accounts have passwords. I guarantee you that yours has one. If you aren't required to type it in every time, that is a convenience provided to you by the software on your computer.)
If you conclude that webmail may be helpful, find out how to access your email via webmail.
If you conclude that IMAP may be helpful, find out whether your email account supports it.

If you're confused or frustrated by something on your computer, I like to say, "You can do it!" You might just need a little encouragement, or information, or change of perspective, and that's where I come in.