The MailStation is a portable, proprietary e-mail appliance manufactured by Cidco. The unit makes brief PPP connections to a (hopefully) local server where it transfers mail in a quick SMTP/POP session with a single button press. Then mail can be read and replied to offline with the software built into the ROM.
The entire unit is 2.2 lbs with a slightly smaller than standard keyboard, a 6" by 2.5" LCD, and external parallel port (for an optional, but non-proprietary, parallel printer). It can be powered by either batteries or an included AC adapter.
The system uses a proprietary ISP which allows up to 5 separate users on one unit, and can't be configured to access through another service provider. The unit costs $99 retail and $9.95 per month or $99.50 for one year prepaid access. It also has a memory for up to 1,000 address book entries and 400 typical e-mail messages, and includes a calculator, calendar, and spell-check in the OS.
The advantages of this unit are its simplicity, for people like my grandfather who don't want to bother with computer ownership in their lifetimes. This is a great tool for them. It's impossible to mess up because except for the dial-up telephone number, only the service provider can change the settings on the unit, and authentication is done using the serial number on the hardware, so there's no problem with forgotten passwords or configuration errors. If the unit resets, just type in the number, dial up the connection, and everything is restored from the central database.
The disadvantages (even for someone like my grandfather) are a 8k message size limit. Anything over that size requires the user to login to the mailstation.com site and view their message with a web browser (although a truncated version is still delivered). But if you have web access, why would you have one of these? The disadvantages to true geeks are obvious, and I don't have to mention them here. This box isn't for you anyway.