If price or platform support are among your concerns when picking a desktop email client, then Mozilla Thunderbird (free) is hard to beat. Though it can't quite match all the whiz-bang features of Microsoft Outlook and that application's full support for Microsoft Exchange mail servers, it will suit a lot of users with a lot of different email scenarios—from those with custom server-based mail to webmail users. In fact, even if you have no email account at all, Thunderbird lets you create one using a choice of partner services, which (for a subscription fee) even let you create an email using your last name as the domain name, like [email protected] That's sure to impress all your contacts!

Signup and Setup

Thunderbird is available for a lot more platforms than Outlook 2013, which only runs on Windows 7 and Windows 8. In addition to Windows 7 and 8, Thunderbird runs on the earlier Vista and XP flavors, as well as on Mac OS X and Linux. In addition, as with Mozilla's Firefox browser an Extended Support Release (ESR) is available for organizations that don't want automatic updates to upset their corporate software setups.

Though you can't set Thunderbird up with an Exchange server's full capabilities, you can hook it up using POP3 or IMAP servers. So if you use AOL Mail, Gmail, Hotmail, or even the new Outlook.com, for example, you'll be able to set up Thunderbird as your mail client software. Checking the Help pages for any of these services turns up the POP3 or IMAP and SMPT (for outgoing email) server addresses for setup. Using Thunderbird instead of the Web versions also means you won't have to look at ads. Yahoo Mail users, unfortunately, have to upgrade to the $19.99-a-year Mail Plus version to get server access.

Like Outlook 2013, the software can automatically determine your required server addresses and settings for the major mail providers. The new account wizard alternatively lets you configure new accounts manually, if you know the server addresses and settings. A more advanced option lets you send and receive digitally signed and encrypted messages, but you'll need valid certificates for this to work. Without those, you can still take advantage of SSL and TLS security.

To create a custom email account, click on the top choice in your folder list, Local Folders, and under Accounts, click Create a new account. This took me to two provider choices, gandi.net and hover.com. Search on your first and last name for these to come up with email matches; Hover actually could create [email protected] for me for $20 a year.

If you're switching to Thunderbird from Outlook, you can import your contact list. It's a simple matter of opening the Address Book, and choosing Tools | Import. In the same step, you'll be able to import your account settings and mail folders.

Interface

Like every email client, you'll see the panel of accounts and folders down the left, the inbox and with an optional email preview pane below or even in the latest layout favored by Outlook, with the preview to the right (from Options | Layout). But you can't get the couple lines preview inside the inbox entries as you can in Outlook. All the panels are completely resizable. You can hide or display the typical menu items, File, Edit, and so on, but you'll probably use the button bar below that most often, for starting a new email, replying, and refreshing the inbox, among other things. Just as in Firefox, you can choose which buttons you want showing and where—thankfully, because the default choices weren't what I was accustomed to. That is, I put the Write (aka Compose) button at top left, replacing Thunderbird's default of Get Mail.

As in Firefox, tabs are the preeminent interface hallmark of Thunderbird. I'm a real fan of tabs in email, which I appreciate the presence of in Yahoo's webmail interface. It's handy to have a search page, an email you're composing, and your inbox all available at the same time from tabs. As with Outlook 2013, you get an Unread button to show only new emails in the inbox.

The application does support conversation view, showing a column of markers indicating which emails are part of conversations. Clicking on the marker expands the conversation, but Outlook makes conversations much clearer, with a triangular arrow indicating them and indentation when you expand them by clicking on the arrow.

You also get one of Outlook's most useful features—the card-like notifications that pop up at the bottom of the screen when a new email arrives. It does this from its system tray icon, but unlike with Outlook, you can't delete or flag the incoming emails right on the notification card. One thing you don't get out of the "box" is automated vacation responses, but an add-on is available to add this capability.

Most mail services have their own spam filters, but Thunderbird, like Outlook, give you a local tool for eliminating unwanted emails. With its "adaptive junk mail controls," you train Thunderbird to recognize mail you don't want. Just check the icon in the Junk column next to any email or click the Junk button in the message preview pane to designate it as such. When you turn this feature on, the program marks suspected junk, but you can and should tell it if it's marked good mail, to improve detection. I found that this mechanism did a good job of detecting worthless emails, but Outlook's similar tool offered more control, with options for several levels of blocking, such as "only the most obvious junk" and using "safe lists only."

Composing Email

When composing an email, you get all the formatting options you'd expect in any messaging software—the full choice of fonts, sizes, and colors for your text. But you can also choose plain text, even forcing that mode for domains you specify.

As with Outlook, I could be composing multiple emails in different windows at once. This is possible in some webmail clients, like Gmail, but less obvious and natural. Thunderbird saves your drafts automatically every 5 minutes by default; you can make this more or less frequent to taste.

Another convenience addressed by mail services like Outlook.com is large attachments. Thunderbird is in on this as well, with its Filelink feature. This kicks in whenever you try to attach a multi-megabyte file to an email. It uses file-hosting services Box, Ubuntu One and YouSendIt to accommodate the outsize files. You can specify the size limit that will trip your file attachment being uploaded to the service you set up with your credentials.

Address Book, Calendar, Chat

Address Book

As I mentioned earlier, Thunderbird can automatically import your Outlook contacts, but it also builds an automatic contact list as you send emails. Nice but missing would be the ability to import from more sources than just Outlook (and even the somewhat obscure SeaMonkey). Just as on Outlook and webmail services, your typing in a message's To: field pops up address suggestions based on your contact lists. A search at the top of the Address Book, window finds any contact quickly.

Though the Address book can't automatically pull in photos and more from a connected social network like LinkedIn, it does offer numerous fields you can fill in—multiple emails and phone numbers as well as physical address, and you can even add a photo for the contact. If you do have a physical address, the Get Map button brings up a Web map for it. You don't get all the phone call tracking features you get with Outlook, though.

Chat

Thunderbird lets you chat with Facebook, Google, IRC, Twitter, or XMPP—but not AIM, one of the most popular chat services. The full-screen chat view shows your contacts' availability, lets you set your own, and displays previous conversations when you log back in. You can create a local alias for each account and have the service automatically log on when you start Thunderbird. When setting up Facebook chat, be sure to use your actual username, the test after facebook.com/ in your General Account Settings

Calendar

No calendar is included with the Thunderbird installation, but you can install a plugin called Lighting for that. In fact, when you choose Add-Ons from the main menu, the first thing you'll see is the entry for the Lightning calendar extension. Install it; after the required restart, you'll be glad you did. Not only will you get a color coded calendar that can import .ICS calendar files and subscribe to Internet calendars, but you'll also get a capable Tasks feature, with prioritization and due dates. You won't however, be able to assign tasks to others as you can in Outlook 2013. Each is accessible from an icon the add-on adds to the top right of the Thunderbird window. The calendar lets you create events and invite attendees, just as Outlook does.

A Powerful Open Source Emailer

With Mozilla's Thunderbird, you don't get Outlook 2013's slick, modern design or social integrations. But you do get a whole lot of useful email tools—and it's free! Maybe most critical for business users is Outlook's full support for Exchange Server features, which, combined with everything else, made it our Editors' Choice. Still, Thunderbird gets a four-star rating, as it's a mature and capable messaging application that's easy to set up, highly configurable, and feature-rich.

More E-mail Reviews:

Best Productivity Picks

Further Reading