If you miss the "Get Mail" button from previous versions of Firefox, you can download an extension to restore it. Also, if you want to change the default mail client associated with the icon or are having problems with it, the following will show you how to fix Firefox get mail icon problems.
Install and Set Up the Firefox "Get Mail" Extension
In order to add the Firefox "Get Mail" icon to your toolbar, you need to download and install an extension. To begin, go to the Get Mail download page (the download is free, but the creators of this add-on do accept donations via a PayPal button on the site). Scroll down close to the bottom of the page and click the Install link.
If you receive a notification that Firefox is preventing you from downloading the add-on, click the Allow button. Click the Install Now button on the Software Installation dialog box.
You will need to restart Firefox for the icon to be added to your toolbar. Make sure to save anything you are working on in Firefox and then click the Restart Firefox button on the Add-ons window.
Selecting an Email Account
You now need to establish which email account you want to be linked to the Firefox "Get Mail" icon. Go to the Tools menu on the Firefox toobar and click on Add-ons. On the Add-ons window, scroll down until you see Get Mail Plus. Click the Options button to open the Get Mail Options window.
Click the Browse button if you want to link the button to an email application on your computer, such as Microsoft Outlook. Navigate to that program on your computer and click Open. To link the icon to a web-based email account such as a Gmail or Hotmail account, type in the web address to that account.
Choose whether you want the email account to open in a new Firefox window or in a tab on the same Firefox window. Click OK to apply the changes.
If you ever change your email account or your Firefox "Get Mail" icon is connecting you to the wrong email account, simply follow these steps once more.
Firefox "Get Mail" Icon is Missing
You may not see the Firefox "Get Mail" icon on your toolbar right away, but don't worry. There is a simple setting that will cause it to appear. Go to the Tools menu on the Firefox toolbar and click on Add-ons. On the Add-ons window, scroll down until you see Get Mail Plus. Click the Options button to open the Get Mail Options window.
Clear the Hide Get Web Mail Menu check box. Click OK to apply the changes.
If the button is still not showing up on your toolbar, right-click the toolbar above the address bar and select Customize. Scroll down to the Customize Toolbar dialog until you see the "Get Mail" button.
Click on the icon and drag it to your Firefox toolbar. Drop it on the toolbar wherever you want to place it. You can add it to the Menu Bar, the Navigation Toolbar or the Bookmarks Toolbar.
Using the "Get Mail" Button
Once you have the Firefox "Get Mail" icon installed, set up, and displayed on your toolbar, using it is a breeze. Simply click on the button and choose your selected action. Click Read Mail to open your email client and check for new mail. Click Get Web Mail to go to your default webmail site. Click New Message to open a new email message window. Finally, select Options to open the Get Mail Options window.
Screenshots taken by and courtesy of author.