1. Do Not Waste System Resources for Mail Checking
Today's email programs are powerful. The wagonload of features comes at a price, though: resources. Many email programs take up lots of memory. On computers with limited resources this can reduce the operating speed, and your efficiency. This is not necessary for periodically checking whether new mail has arrived.
Email checkers are designed specifically for that task. They do not have all the features of full-blown email clients because this is not necessary. Instead, email checkers are small programs that use little resources doing their job.
2. Delete Unwanted Mail Directly from the Server
When you set up your email program to check for new mail periodically, it will usually not only look whether anything new has arrived, it will also download every message automatically.
This is great if you do not mind receiving 20 MB attachments that are a virus, or obvious harassment from spammers. If you think downloading these messages in full is not necessary, a sophisticated mail checker can help.
It displays the headers (who sent the message, what its subject is, how large it is) of all new messages on the server and allows you to delete unwanted mail directly on the server. When you launch your email program later and download all messages, all the unwanted ones have already been removed.
3. Less Distraction through Filters
If your email client checks for new messages all the time, you will get interrupted just as often. If you set your email client to check less frequently, you'll learn about important messages later, too.
A mail checker that includes filtering capabilities can announce only certain messages (mail from your boss and your daughter, for example). You'll get distracted less while you'll know about the important messages instantly.