by Les Jones <firstname.lastname@example.org>
America Online overhauled their email system a few weeks ago to better handle long messages, and to allow AOL users to send and receive files through Internet email (see TidBITS-292). The new system delivers some long-awaited features but also has a few snags.
Long Messages -- By now TidBITS readers on AOL have noticed a change in the way TidBITS arrives. Previously, email messages longer than about 25K were split into multiple messages as they passed through AOL's Internet mail gateway. TidBITS issues are about 30K, so AOL users used to receive TidBITS in two parts.
In the new system, messages larger than 25K appear as downloadable file attachments. AOL displays the first 2K of the message in the message body as a preview of the file contents. The message header makes note of this:
X-Note: Only the first 2K of this message is displayed. You can
retrieve the entire text by selecting "Download."
At first, AOL included the first 25K as a preview. That led to howls of protest from many who disliked the extra download time. AOL took note, and reduced the preview to 2K.
Unfortunately for Mac users, AOL's attached text files are formatted as DOS text files, so they contain linefeed characters that usually appear as small boxes at the beginning of each line. You can strip out the linefeed characters using a number of utilities, such as Add/Strip or Dos2Mac. You can also read the files in a text editor like BBEdit Lite that transparently handles linefeed characters.
According to America Online representative Meriam Grossman, AOL will eventually allow users to choose how they receive long email messages: split, or as file attachments with a 25K preview. Meriam commented that AOL is working on the linefeed problem. Version 3.0 of the AOL software for Macintosh will revise the entire email interfac, include an integrated Web browser, and might be finished by the end of 1995.
Internet File Attachments -- America Online has always made it easy to send files from one AOL member to another. AOL now offers support for file attachments to and from the Internet. Superficially, Internet mail file attachments work just like AOL file attachments. Beneath the surface, however, there are important issues that determine whether the file will still be useful once it has passed through AOL's email gateway.
To perform binary-to-text conversions, AOL uses MIME (Multipurpose Internet Mail Extensions), sometimes known as Base64. Mac users are probably more familiar with BinHex than MIME. Like MIME, BinHex transforms a binary file into a text file that can safely pass through 7-bit email systems. BinHex also understands the Mac's two-part file format (data and resource forks), and preserves a Mac file's name, along with its type and creator codes.
MIME can be extended to handle BinHex, but AOL has not yet implemented BinHex in their email gateway. That means trouble for Mac users until AOL fixes their system. Will Mayall, a programmer for Claris Emailer, was mystified over the omission of BinHex. "The one thing I can't figure out is [why AOL didn't do] Binhex. It's not hard coding, and it's the standard way people send Macintosh files over the Internet."
Testing the System -- I mailed files back and forth between AOL and my Internet account, using both Eudora and Claris Emailer. All attachments sent from Eudora were MIME-encoded and used the BinHex format rather than AppleSingle, AppleDouble, or UUEncode. For the experiments, I used four document types: an unaltered application, a StuffIt-compressed application, a binhexed application, and an unaltered GIF.
AOL's email gateway wrecked the unaltered application going from AOL to the Internet. Without using BinHex, the application's resource fork was lost, rendering the file unusable. So, sending unaltered Mac programs and Mac files with resource forks (such as some HyperCard stacks and documents) out through AOL's Internet mail gateway is suicide.
Next, I tried a StuffIt-compressed version of the application. Compressing the file produces a new file with only a data fork, and the resource fork is restored when the file is decompressed. This worked, but my test file's type and creator codes were lost when it arrived at my Internet account, so double-clicking the file didn't work to expand the file. Dragging and dropping the file onto StuffIt Expander's icon also failed. I had to use File Buddy or ResEdit to add the StuffIt type and creator codes (SITD/SIT!) before StuffIt Expander recognized and successfully decompressed the file.
Binhexed files work well in either direction. StuffIt Expander doesn't insist on type and creator codes for binhexed files because the type and creator codes are almost always lost anyway. After downloading the binhexed file, I could drag and drop it onto StuffIt Expander and achieve success every time. Aladdin's DropStuff utility can compress and binhex files in one easy step.
Finally, I tried sending GIFs back and forth between AOL and my Internet account. This worked surprisingly well. Eudora correctly typed the file for me, so I could double-click it to open it. AOL recognized the file was a GIF, and even displayed it during the download. I have high hopes that all Internet mail attachments will work this smoothly once the bugs are worked out. To be fair, GIFs are a ringer. AOL's gateway automatically recognizes GIFs, JPEGs, and MPEGs.
Other Notes -- Text of binhexed files less than 25K in size arrived in my AOL email within the body of the message I attached them to. When binhexed files arrived in the message body, I saved the email as text and ran it through StuffIt Expander without a hitch.
AOL's email system allows only one attached file per message. If an incoming email has multiple file attachments, AOL stores the files in a single attached MIME file that can be converted with a utility such as uucd (Adam and I both had troubles with MPack). Once again, AOL makes note of this in the message header:
X-Note: This message has multiple attachments, stored in a
single MIME document. Select "Download" to get the MIME
document, then use a MIME decoder (available at keyword
FILE SEARCH) to retrieve the attachments.
Conclusions -- AOL's Internet file attachment is sure to make life easier for AOL members and their friends, but the new system needs to be updated for proper BinHex compatibility. Until AOL updates their system, convert files to BinHex format before mailing them through AOL's Internet mail gateway.