GMail Notifier loads a small envelope icon into the menubar. A drop-down menu allows you to monitor your Google Calendar, poll your Gmail account for new mail, jump to your inbox or to the compose window in Gmail’s web interface. If it detects unread mail in your Gmail account, an unread message count appears in brackets next to the icon. Tiger. Leopard.

Gmail+Growl is an expanded version of GMail Notifier, which works with Growl to provide “flash-up notifications” on your screen as mail arrives for you in your GMail account. Rather like Mail Appetizer does for Apple Mail. Growl is a program that provides notifications, or on-screen messages, when events occur in programs. You will need to install Growl as well for this to work.

HTTPMail allows you to send and receive email from MSN and Hotmail servers. It comes in Jaguar, Panther and Tiger flavours. Once installed, various Hotmail-type options can be configured in its Apple Mail preferences pane. It is freeware. It is possible that this will only work with loder Hotmail accounts or "Premium" Accounts. See the long discussion thread on the Apple Discussion Board.

iAlert is a system preference pane that enables notification for a range of apps, including iTunes, Safari, Firefox, Thunderbird, Entourage and most importantly, Apple Mail. It runs on top of SIMBL (Smart InputManager Bundle Loader), the same Cocoa application hack that powers the Safari plug-in PithHelmet. A copy of SIMBL in included in iAlert’s disk image and must be installed first. Very pretty smoked-glass alerts. No longer supported.

iFaces is a notification utility for Apple Mail that lets you know about new email by displaying the Address Book image of the sender on the Desktop. The Preferences screen allows you to set a number of options including the transparency of the pane and a custom image for emails from people without pictures in your Address Book.

iNotify.saver is a screensaver that polls your Mail.app accounts (.Mac, POP and IMAP all supported) for unread messages and keeps track of the number of your iChat buddies who are online. You can run it over a “basic black” background or over one of the preset Mac OS X screensavers. It does look nice.

Notify.saver is freeware, although the developer warns that it may cost you karma if you use it a lot without donating.

MacBiff is a “biff” program that sits in the menubar and polls multiple IMAP accounts for new mail. Unlike many notification utilities, though, it takes full advantage of the functions and flexibility of IMAP servers and folders, allowing you to choose which folders it should watch. The ability to open a message in Mail.app from the subject line displayed in MacBiff would make it even better, but if you are looking for a powerful and flexible mail-check utility for your IMAP accounts that also works with Growl, you will want to check this out. MacBiff is freeware.

MacFreePOPs is a stand-alone app which allows you to download your emails from web-based mail services like Yahoo, hotmail and Gmail. It is a version of the FreePops app for Mac OS X 10.2 and above, and works by translating local POP3 requests into HTTP actions. It currently offers support for Yahoo!, SquirrelMail, hotmail, Gmail, AOL, lycos.co.uk and others, and more are planned. It is freeware.

MailAppetizer displays a splash screen when a new email arrives, complete with header info, the initial text of the email and an Address Book picture of the sender if you have one. Options at the bottom of the splash screen allow you to view the message in mail, mark it read, delete it, or dismiss the notification window. Download the latest version (1.2 beta 4) from Bronson Beta.

MailCountX. Another utility that tracks your unread emails and displays the total in the menubar. Not as polished as MailUnreadStatusBar nor as customisable. It's been in beta since December 2003, which doesn't bode well for future development. I list it here for the sake of completeness, although I can't see why any one would choose to use it. Download it from SqueakSoft.com.

Mail Forward is a stand-alone app that will forward your email from AOL, Gmail, Hotmail, MSN, Yahoo! or from any POP account (to, say, Apple Mail). It doesn’t work with as many providers as MacFreePOPs and it’s not donation-ware, but to me it seemed easier to configure and use. It works by accessing your web mail or POP mailbox and then forwarding each email onto your chosen account through your SMTP mail server.

Mail Status Control displays the number of unread messages in Apple Mail next to its icon in the Statusbar. The message count display can be configured to show only the inbox or all unread messages. Mail Status Control has a number of other settings that you can determine, including the ability to set keyboard shortcuts for checking mail, launching a new message and showing Mail.app

MailUnreadStatusBar.This excellent plug-in puts a little icon of the Apple Mail stamp in your menubar that lists the number of unread emails you have. You can customise which folders it tracks, and the icon's drop down menu lists the unread mail by folder, allowing you to jump right to the folder you want or need to read. It's my favourite utility of its kind, and it's free. Download it from QueueSoft.

Mail Unread Menu sits in your Menubar and polls for unread messages at a user-definable period. When it finds some, the number of emails is displayed next to its icon. Menubar utilities like this are less distracting than the notification provided by Growl or Mail.Appetizer. Mail Unread Menu only works if Mail.app is running. The most recent version adds an option to monitor all mailboxes or just your inbox. Universal binary and freeware (donations not refused).

MailWidget checks your POP3 email account every time Dashboard is activated — without having Apple Mail running all the time. It remembers which email was received the last time Apple Mail was started; other widgets might say something like “there are 88 messages on the mail server” but only MailWidget will tell if there are new emails that hadn’t already been received by Apple Mail.

PowerMate MailPulse is a widget for Konfabulator (remember that?) which checks Mail.app for unread email every specified number of seconds.

When you have unread mail, your Griffin PowerMate will pulse depending on how many unread emails are in your inbox(es) until all new mail has been read. Obviously you need to have a Griffin PowerMate for this to be useful.

Spoken Notification of new mail. Todd Ditchendorf has written an AppleScript which, when attached to a rule in Apple Mail, will speak the name and sender’s email address. By default “Victoria” does the talking, but you can set it to any of OS X’s voices by editing the script. Todd provides instructions on his blog for setting up the rule to launch the script.

Widgets. Notification widgets for Tiger are numerous. There are at least five for GMail alone, of which GPeek seems to be the most flexible, although GMail Checker is cute. eCheck claims to poll almost any kind of email account in existence, but costs money. Other notable widgets include MailPop which checks GMail and promises .Mac support soon, flores which adds a flower to a virtual vase for every unread email, and My Yahoo! for mail and headlines from a yahoo account. I could go on, but I won't.

Ymail provides menu-bar notification for emails in your Yahoo! Mail account. Like Gmail Notifier for Gmail users, it offers a much better notification option (IMHO) than the various widgets that do the same job. Launching the app loads a “Y” into the menubar which provides a drop-down menu full of options. It's a good option for those times and in those environments when you can’t use Apple Mail. Ymail is free and open source (the code is also available).