What are MIME e-mail messages for and how do I open them?

Posted By : of Data Doctors on January 22, 2004

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What are MIME e-mail messages for and how do I open them?


This question was answered on January 22, 2004. Much of the information contained herein may have changed since posting.

MIME stands for Multipurpose Internet Mail Extensions and it is a standard that was created in 1992 that allows various types of files to be exchanged between many different e-mail systems and programs.

The MIME standard introduced the ability to allow more than just plain text to be exchanged between different e-mail systems Without it, sending photos, sound files, video clips or many types of spreadsheets and documents via e-mail would be much more complicated or in some cases impossible to do.

MIME converts ‘binary’ files (non-text files such as pictures, audio, video, etc.) into encoded text files so they can be sent via the e-mail system (which was originally only designed to work with text files).

MIME is what allows an AOL user to send a picture or video file to an Earthlink user or any other non-AOL Internet Service Provider and have it transfer properly through both systems.

Think of the process like the transporters in the old Star Trek series When Captain Kirk would say ‘Beam me up’, he was converted into tiny bits of ‘who knows what’ at one end and reassembled at the other end because the ‘encoder’ and ‘decoder’ used the same ‘algorithm’ to complete the process.

This common standard is generally built into most of today’s e-mail programs, so opening these files is taken care of in the background automatically However, because it is an encode/decode process that relies on everyone following the ‘standard’, things can go wrong from time to time.

If you are using older e-mail programs (especially AOL, Juno or other webmail systems) that do not have MIME support, you may find that you are getting ‘MIME’ attachments (.mim or .mme files) that you can’t open.

In order to open these files, you will need to install a ‘decoder’ program such as the popular WinZip compression program (www.winzip.com) for Windows users or Stuffit (www.stuffit.com) for Mac users.

Once one of these programs is installed, every time you click on MIME files, it will automatically open the decompression program and show you what is inside of the file Often times, several files will actually be in the ‘package’ because the sender sent multiple pictures or documents.

You can also check the ‘help’ section of your e-mail program (AOL users can get more info at keyword: MIME) for more specific instructions in dealing with MIME files.

There is also a S/MIME standard that is known as ‘Secure’ MIME which allows for secure encrypted e-mail messages These types of messages require an ‘RSA’ public key encryption program to decode the message and will generally refer to that fact within the message header or subject line.

Since standard e-mail messages are viewable by anyone that is in the path of the message (mainly employees at the hundreds of ISPs that will handle the message), senders that want to make sure only the intended recipient will ever be able to see the actual message can use an encryption program like PGP (Pretty Good Privacy - www.pgp.com) or the freeware version available at http://web.mit.edu/network/pgp.html.

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Posted by of Data Doctors on January 22, 2004

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