Retaining emails before dumping my ISP,

[five.five-six]

[bigbearbear]

Download and install an email software on your local computer, for Windows you can download Windows Live Mail from Microsoft:

http://windows.microsoft.com/en-us/windows-live/essentials-other-programs

Configure it to connect to your current email provide by your ISP. Look for instructions on how to connect via POP3 or IMAP, those are the most commonly provided connection method.

Once you're connected you can download the email to your and pretty much keep them forever.

[bigmike82]

Thunderbird plus imap will do it.

Outlook, if you have it, will do it as well and let you save the emails into a PST archive (which, despite its problems, is still the preeminent email storage format out there).

[den888]

Also, you should open a web-based email account (gmail, Yahoo) so that your email is not ISP dependent.

[NoSpam]

It depends on how you're currently receiving your email. If you access your email through a webpage, all your email is stored on their server. To download everything, you just need to configure an email app on your PC to download your mail. You will need the following information:
1) your email address
2) your password
3) your ISP's incoming mail server
4) your ISP's outgoing mail server

You will also need an email app. Windows comes with Microsoft Outlook express. Mac OSX comes with an app they call "Mail". As long as you have the required info listed above, you can find thousands of guides online on how to configure your email app. Your ISP probably already has a guide on their website on how to do this. Alternatively, you can call their support line and they will usually walk you through the whole process.

[NoSpam]

I forgot to mention that if you're already using an app for your email (not a webpage), then you probably already have all your mail downloaded to your PC. If you ever change ISP's, then you will continue to have all that mail, but not have access to send/receive new mail. If that is the case, you just need to update the required information in your app with your new email info, and can continue to use the same app with all your old emails available to you.