by Curtis Clark
Eudora - an e-mail client that runs on the machine on your desktop. It sends mail to an SMTP server, gets mail from a POP3 server, and stores and manages mail on your computer.
POP3 - Post Office Protocol 3, an e-mail server that runs on a "big computer" such as the Academic or Administrative clusters ("Vax"). It transfers e-mail messages from storage on a mail server computer to Eudora or another e-mail client.
SMTP - Simple Mail Transfer Protocol, an e-mail server that runs on a "big computer". When it receives mail from Eudora or another e-mail client, it passes it on to the SMTP server at the destination of the e-mail. When it receives e-mail from another SMTP server, it stores it.
What happens when you send mail:
What happens when you receive mail:
After you have installed Eudora, there are certain pieces of information it needs in order to send and receive e-mail. If your copy of Eudora works, this information is correct, but I'm providing it here in case you have problems, or need to set up a new copy, or switch to another POP3 server (such as the Intranet).
All of this information is entered through the Tools | Options menu choice.
The dialog that it produces has a bunch of picture icons of categories with
names like "Getting Started", "Personal Info", and such.
In the table below, the left column is the name of the category, the middle
column is the item that you might need to change, and the right column is
the value to type in. All the rest of the entries are normally left as is.
clstac = Academic OpenVMS Cluster, clstad = Administrative
OpenVMS Cluster, intranet = Intranet, items in italics are
for explanation, not information to be entered. Some items appear on more
than one dialog, but when you change them once, they change everywhere.
As installed, Eudora has three "mailboxes", In, Out, and Trash. When you write a letter, it is saved in the Out mailbox (you can turn this off by unchecking Tools | Options | Sending Mail | Keep copies). New mail ends up in the In box. And when you delete a message, it ends up in the Trash, which is ordinarily emptied when you exit Eudora (you can change with Tools | Options | Miscellaneous | Empty trash when exiting).
If you only use these three boxes, you may find yourself with an overflowing In box (of course it doesn't really overflow, it just expands until it takes up all the space on your disk). Or you may routinely delete messages to cut down the confusion, and then wish you had them later. But Eudora lets you create more mailboxes, and you can use them to help impose order on all the mail you save.
Let's say you're looking at a message you'd like to save. From the menu, choose Transfer | New, type in a name for the mailbox ("facnet", for example), and hit OK. From now on, the Transfer menu will include the choice "facnet", and you can transfer messages there easily. To get to the new mailbox, choose Mailbox | facnet. With recent updates of Version 3, and high-resolution monitors, you may see a tree display on the left of the Eudora screen, that shows all your mailboxesdouble-click one to open it.
Just back from vacation, with several dozen new messages? Create a mailbox called "answer" and put in it all the mail you need to answer. If you have a group of related mailboxes, you can create a folder ("Make it a folder" on the create mailbox dialogue) and drag mailboxes to it (if Eudora is asking you for the name of a mailbox in that new folder, and you don't want one, just hit Cancel).
A byte consists of eight bits, and each bit is a single "binary digit" (1 or 0). Computers represent "characters" (letters, numbers, and punctuation) as bytes, either one byte per character (the standard on most computers) or two bytes per character (Unicode, on Windows NT and maybe elsewhere). Because a byte is eight bits, there are 256 possible bytes, 0-255 (computers always start counting at 0). But look at a keyboard and you'll see only 52 letters (upper and lower case), 10 numbers, and 34 other symbols (including the space bar and delete key), for a total of 96 characters. For reasons that I won't go into, the first 32 byte values (0-31) are used for arcane and often obsolete communications functions. With the next 96 being characters, the "keyboard character set" has 128 characters (0-127). This is only half the possible bytes. As it turns out also, you can represent these 128 characters with only seven bits, since the first bit of the byte will always be 0.
The remaining 128 bytes (128-255) also represent characters, but not ones on the keyboard. Depending on the computer, they can be accented characters, "line-drawing" characters, true typographic quotes and dashes, or other symbols.
But all 255 possible bytes can also be used for two other totally different types of information: non-character data and instruction code.
Non-character data generally consist of numbers. When I type 1997 here, I am typing numerals, which are just another type of character. Computers can't do math directly with numerals. Instead, they work with actual binary numbers that, according to several different schemes, represent the ordinary decimal numbers we work with. A binary number consists of bits, but the computer can organize these into bytes just as it does for characters. If we wrote the integer 65 as a binary number, it would look like 01000001. The computer could do arithmetic with this number. But this is also the byte value for "A". So 01000001 can be either a number or a character. Numbers can occupy any of the possible byte values, so it takes all eight bits to work with numbers.
These non-character data are the substance of many kinds of computer data files: graphics (where the numbers can represent the amount of red, green, and blue in a pixel), sound files (where they are times and frequencies), spreadsheets (where they are not only the numbers in the sheet, but also the information about fonts, lines, formulas, etc.), and even word processing files (font attributes, etc.).
Instruction code is what tells the computer what to do. In one computer, 01000001 might mean "add registers A and B", and in another it might be part of a multi-byte instruction. Computer code also contains data, since 01000001 could also be part of a memory address. Code also uses all eight bits.
So the bottom line is that non-character data use eight bits, code uses eight bits, the full character set uses eight bits, but the keyboard characters only use seven bits. Now if you were designing a system for e-mail communication, would you design it to use eight bits, or seven bits? Obvious answer. But let's say you had to pay by the bit. You might decide that seven is enough. That is exactly what happened in the early days of e-mail.
So when you send information by e-mail, you can only send the first 128 byte values. You can't send code or non-character data directly. but you can send it if you "encode" it: translate it into some form that only uses seven bit characters. (A simple way to do this would be to break it up into two 4-bit chunks. 10110110 would become 1011 and 0110, which you would fill out to seven bits-0001011 and 0000110-and send, and the recipient would remove the first three 0s and put it back together. Of course, you'd write a program to do this automatically.)
Almost from the moment that 7-bit characters became the standard for e-mail, people have been devising ways to do just this. Eudora actually handles four different kinds of encoding, and it does all of them more or less automatically.
One type of encoding is used to handle punctuation and letters that are not part of the basic 7-bit codesuch as this "em-dash", these typographic quotes (which aren't the same as these "typewriter" quotes), and accented letters (åëìôúçß). As a test, I sent myself the following email message:
(some of these may look strange on older web browsers)
And read it with a program that doesn't support this type of encoding. It looked like this:
aeiou =E1=E9=ED=F3=FA =E0=E8=EC=F2=F9
=E4=EB=EF=F6=FC =E2=EA=EE=F4=FB =E5=E7=
You may have seen these codes in e-mail messages before. Even if your program decodes such things, it may not do so correctly - Windows and Mac use different character codes for many of these. If you work with Windows, and havenÕt been able to understand why you're seeing an Õ in a word, that same character code on a Mac makes the typographic apostrophe. I'm sure Mac users see similar oddities. Fortunately, Eudora seems to handle decoding well.
The other three methods are used for "attachments": files that are sent inact as part of an e-mail message. They are uuencoding (the "uu" stands for "Unix to Unix"), binhex, which began on Macintoshes, and MIME (Multimedia Internet Mail Extensions), or more specifically a coding scheme that is part of MIME called Base 64. When you send a message in Eudora, you select the enoding type in a drop-down box on the New Message window (Windows 95 version pictured):
When you receive a message in Eudora, it automatically decodes the attachment and puts it in a folder called Attach inside your Eudora folder. They also appear as icons (or text in some versions) at the bottom of the message. You can double-click one of these and often it will open with the application that created it.
If you correspond only with others who use Eudora 3, the single problem that may arise is that sometimes if you send an e-mail message that has an attachment and nothing else, it may not decode. The way to avoid this is to always put some text in the e-mail message, if only "here's the attachment you asked for."
If you correspond with people who use other e-mail programs, or sometimes use other programs yourself, attachments can become a problem, specifically when they don't decode. Below are examples of the three different encoding formats. You will never see these in Eudora, since it will automatically decode them; I created them by sending attachments to myself and reading them in another e-mail program that doesn't decode them.
Here is MIME. You can tell because it says "Content-Transfer-Encoding: base64" which is the MIME standard. Following the header, the lines are 76 characters long, and can begin with any letter or number.
—=====================_869974979==_ Content-Type: image/gif; name="Cptree.gif"; x-mac-type="47494666"; x-mac-creator="4A565752" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="Cptree.gif" R0lGODlhNAEyAYABAAB/AP///yH5BAEAAAEALAAAAAA0ATIBQAL/jI+py+0Po5y02ouz3rx7DhzA SJbmZI5imrBLGiLwO8ukUuOw2+7+BwwKbb4bg3eSFJOBnCPHOzpppcbS2Iwqp8Nu57dlErEXrdW8 qvbUT3SarYNT5efimu71qupvsGHXkic4SBix1CYWh1co5TbGCBkpKZkY5RhJNgaYNglydRX0CdoZ irQotLgZSAoh6voKGys7ylqXqemnIapYO/fJ6Aoc3KuYSPx3W/t7zNxo19wHmAutd0h97axKnGy4 1y1LCY49nv1KrqvKPTSrfu7eyv7+dUoxLH8fvjwfXy5eRvvO2CCB5PRZaIeBHT1E0wLCOvgQH7Jn CfmF0ZYBoLIY/xUV2oPIsZfGbwr7xerYcFJEFP5YfiQ1cgPFdQgfGBQ5K9pMeC1xWkN5iWdInTVB /gR61KVFhrsqrPwXs5lHb0BuGu3pa6dJjEyfIuWyb6ktq2G55onY1GbarkkFRa368o1RD2+FlVRb d2JeQm1lplSKEOxXgiq9FvuLy2ynvXyp1iv6gWy+vGuzKsbE+CpWuXFgmsPc9w5iooTPxi01lFPn sZvdTpUs+rJerYcFx35tu5pHtiexfXa6FzbphZZDb5vahbjEi6OzBM+8vBsz2tEBy5593Tn16mGK 5/aemsriU5Uga29+/nrlx+rglEZ1O3VQv99Nm39EcvvwmsKFZv/TNJlxkXHVn0QF9rced4m9t4KB
—=====================_869975006==_ Content-Type: application/mac-binhex40; name="Cptree.gif" Content-Disposition: attachment; filename="Cptree.gif" (This file must be converted with BinHex 4.0) :#N0`G(*PC5jRD@B!4dP’CNT@9e)!!!!!%3B!!!!![N&(58Bi1@%d!6)"J!%!!(m !rrrr)IN%!3!!!3!X!!!!!$3"-J&!![q-MkR,l3qMR,6DLl2H[(X1(-")PZCNMQ+ DX%XD)[!lbk45il$El[i($!TY[KZ$Gj)8Ni’F)mFl1QQPaY,BM#UR`flRYf85X4H YeEbUpY42G*UYJe2Pjq+Dl[@UkQq`BGH5*cK)’,(8*KD(9bMP0XB)’5NTQ4MP’%N f"TJf#A*e&I3*fKQ+Y#LdZ"P)#L(UqJSE+c[+@THTkDFKUPJlpmRS#KcFUjK)r(G Eqh[-h’MAh!HB#keh5(hYV%UFE,MA,8X*MMfHr8UZUmSp0+YqlYl+r[je5M%XIaq q2"pI,Pj’qmlB))(Np&PSKi%G2866!X)kq"!IXQF*qBA4PJ’JXKMr&4ADJmLaPmC [#[[&kYK`8N38rPKq*$9b!m9e#"mB&$NVfNai,A&D3hQ*CdLG08(q"(V8T8@’ZbU Xr"HcQ8G[3’iDlHPVTdQ-6*mLjE*[U5fVBERQLGM8CYUZ539&VIVbM9%2Ei@99&Y hBPj#E@@Q9)S3l&H#+Vd@qi[,E+HpI+R@+rU"E,kmDl-UaX6i+PDjF@#D`pch$Q+Last is uuencoding. Lines are 61 characters long, and always begin with "M". Statements like "begin 600 Cptree.gif" also indicate uuencoding.
—=====================_870180781==_ Content-Type: image/gif; name="Cptree.gif"; x-mac-type="47494666"; x-mac-creator="4A565752" Content-Transfer-Encoding: x-uuencode Content-Disposition: attachment; filename="Cptree.gif" begin 600 Cptree.gif M1TE&.#EA-`$R`8`!``!_`/___R'Y!`$```$`+``````T`3(!0`+_C(^IR^T/ MHYRTVHNSWKQ[#AS`2);F9(YBFK!+&B+P.\ND4N.PV^[^!PP*;;X;@W>2%).! MG"/'.SIII<;2V(PJI\-NY[=E$K$7K=6\JO;43W2:K8-3Y>?BFN[UJNIOL&'7 MDB<X2!BQU"86AU<HY3;&"!DI*9D8Y1A)-@:8-@ER=17T"=H9BK0HM+@92`HA MZOH*&RL[REJ7J>FG(:I8._?)Z`H<W*N82/QW6_M[S-QHU]P'F`NM=TA][:Q* MG&RXURU+"8X]GOU*KJO*/32K?N[>RO[^=4HQ+'\?OCP?7RY>1OO.V""!Y/19 M:(>!'3U$TP+".O@0'[)G"?F%T98!H+(8_Q45VH/(L9?&;PK[Q>K8<%)$%/Y8 M?B0U<@/%=0@?&!0Y*]I,>"UQ6D-YB6=(G35!_@1ZU*5%AKLJK/P7LYE';T!N M&NWI:Z=)C$R?(N6R;ZDMJV&YYHG8U&;:KDD%1:WZ\HU1#V^%E51;=V)>0FUE MIE2*$.Q7@BJ]%ON+RVRGO7RIUBOZ@6R^O&NS*L;$^"I6N7%@FL/<]PYBHH3/Why is all this important? Because you'll need to know how a file was encoded to know what kind of software you need to decode it. There are different decoding programs for Windows and Mac, and different programs for each method, as well as programs that do all three. Use of these is beyond the scope of this tutorial, but knowing the kind of file you are looking at is the first step in asking for help.
Space for this page is provided by California State Polytechnic University, Pomona. Although it is intended to further the educational mission of the University, the opinions expressed here are those of Curtis Clark, and do not represent official policy of the University.