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Question: What is a attachment?
Answer: An attachment is a document that is sent along with an e-mail. Attachments are created with OTHER computer programs. E-mail is like sending a letter and an attachment is like sending a package by UPS. Both are delivered to your address -- you just might need a little help opening those packages.

E-mail is primarily a text based system. However there are times it is essential to receive or send other types of information (e.g. programs, pictures, word documents, spreadsheets, and databases). In order for these "binary" files to be sent via e-mail, they must first be converted into a text equivalent. Remember e-mail is a text based system. This conversion is called "encoding" and is required for sending an "e-mail attachment".

Sounds easy enough - however - there are many potential pitfalls that can be major stumbling blocks for the receiver of these files.

If you send an attachment please follow these rules:

    My Rules i.e.: it's not the law but I wish it was.
  • Indicate what program you used to create the document.
  • Indicate how the document was compressed (if it was).
  • Indicate what the file name is.
  • First - You need to make sure the file you're sending is in a format that can be read by the person on the other end. If you wrote it in Word 97 - does the person have Word 97 or should it be saved as a text file (for example).
  • Second - you need to make sure that the method of encoding is something that the person at the other end is capable of handling. That means finding out what kind of "decoding" system is available on the other end.
  • Third - If it's a large file, you may need to compress it - which makes it smaller (taking less time to download) but also brings up the another issue of format.
  • Fourth - finally (hopefully) - not all online services can handle attachments - so it is important to know your service's limits before you try to send a file. Some services only allow attachments less than 100k for instance.

There are several different encoding standards in widespread use. The most common are:-

  • MIME:- This is a newer standard. You should choose MIME where you have the choice. What is MIME? MIME, the Multi-purpose Internet Mail Extensions, is a freely available specification that offers a way to interchange text in languages with different character sets, and multimedia e-mail among many different computer systems that use Internet mail standards. If you were bored with plain text e-mail messages, thanks to MIME you now can create and read e-mail messages containing these things: character sets other than ASCII enriched text images sounds other messages (reliably encapsulated) tar files PostScript FTPable file pointers other stuff MIME supports not only several pre-defined types of non-textual message contents, such as 8-bit 8000Hz-sampled mu-LAW audio, GIF image files, and PostScript programs, but also permits you to define your own types of message parts. Before MIME became widespread, you might have been able to create a message containing, say, a PostScript document and audio annotations, but more often then not, the message was encoded in a proprietary, non-transportable format. That meant that you couldn't easily handle the same message on another vendor's workstation, or even get it intact through a mail gateway in the first place. Now, depending on the completeness of your MIME-capable mail system, there's a good chance that it'll "just work." (See section 1.2 of the original source FAQ for some warnings on this subject). One of the best things about MIME is that it's a "four-wheel drive protocol", (to borrow a description applied originally to PhoneNet by Einar Stefferud). MIME was carefully designed to survive many of the most bizarre variations of SMTP, UUCP, and other Procrustean mail transport protocols, such as BITNET and MMDF, that like to slice, dice, and stretch the headers and bodies of e-mail mess
  • UUENCODING:- Is another popular format that originated on the UNIX system.
  • BINHEX:- .hqx This is the standard encoding used on Macintosh systems. What is BinHex, and how can I decode it? BinHex is short for "binary-to-hexadecimal". It is the most common Mac OS file conversion process, combining the data and resource forks of a file and converting it from its binary form to an ASCII text file. BinHex conversion allows you to send word processing, spreadsheet and application files via e-mail or FTP. BinHexed files take up more space than the original files but are far less likely to be corrupted in transit. Recognizing BinHex files A BinHex file can usually be identified by the .hqx extension at the end of its name. Looking at the contents of a BinHex file, you will notice that it has a message on the first line identifying it as BinHexed, followed by many 64-character lines made up of seemingly random letters, numbers, and punctuation marks.
  • MAC BINARY: -.bin MacBinary II (often, just MacBinary) is a file conversion process that combines the data and resource forks of a Mac OS file, protecting its integrity when transferred to non-Mac OS computers. Compared to BinHex, a MacBinary file is somewhat more susceptible to corruption, but because it is not converted into ASCII, also takes up less disk space.
  • Base64 Another MIME format is "octet-stream" or "base64". This format is used for binary files (i.e., files in which little, if any, of the text is printable). A base64 encoded message will include lines similar to the following (not necessarily in the header): Content-Type: application/octet-stream; name="filename" Content-Transfer-Encoding: base64 The binary data will look something like this: ICAgIOwgIFoGRCDxUVVBRENBU0UgTTtBO0oNClsxXSAgICCmQ29udmVydHMgdGhlIGNhc2Ug b2YgcXVhZCBuYW1lcyBpbiBhcnJheSAXDQpbMl0gICAgpiBDb252ZXJ0cyBuYW1lcyB0byB1 cHBlcmNhc2UgaWYgRD0xLCB0byBsb3dlcmNhc2UgaWYgRD39MQ0KWzNdICAgIKYgSWYgRD0w LCBjb252ZXJ0cyBuYW1lcyB0byB0aGUgcHJpbWFyeSBhbHBoYWJldCAo8UFMUEhTWzE7XSkN

    Note that by default all email attachments will go into the Eudora directory. We would suggest that users should reserve a directory on their hard disk specifically for files that they download. You may wish to create another directory and call it "in box", "incoming" or something similar.

    To specify this directory, go to the "Special" menu, select "Settings", select the "Attachments" category, and click on the "Attachments directory" button. In the resulting dialog box, select your special directory and click on "Use directory". From now on, email attachments will be saved into that directory.

    Special Note: Be careful with the files you receive as email attachments. Executable programs (ending in .exe and .com) could contain computer viruses, which would only be released when you execute them. If you see unknown or un-requested executable files in your attachment directory, you might wish to delete them.

    If you find that all the above seems too difficult, or that the file does not seem to decode properly, then your best recourse would be to send an email back to the sender, letting them know that were errors in the attachment, and could they please re-send the file using MIME encoding.

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