Section 5.4. Transfers by Email

5.4. Transfers by Email

Although sending files as email attachments might seem to be a logical plan, it's very slow. Furthermore, remember that most email providers limit your attachment size to 5 or 10 megabytes. Trying to send more than that at once will clog your system. If you've got a lot of stuff to bring over from your PC, use one of the disk-or network-based transfer systems described earlier in this chapter.

But for smaller transfer jobs or individual files, sending files as plain old email attachments works just fine.

If you have trouble, or if you can't open the attachments at the other end, consider the following potential snags.

5.4.1. File Compression and Encoding

The technology behind email attachments is somewhat technical, but it's extremely useful in understanding why some attachments don't make it through the Internet alive .

When you send an email attachment, your email program does two things. First, surprising as it may seem, the Internet cannot technically transmit files only pure text. Your email program, therefore, takes a moment to encode your file attachment, converting it into a stream of text code to be reconstructed by your recipient's email program.

This encoding business is a problem chiefly when sending files from a Mac to a Windows machineand only rarely a problem, at that. The Mac can understand almost any encoding formatMIME, Base64, AppleDouble, whateverbut Windows machines don't understand something called BinHex. If your Mac-to-Windows attachments aren't coming through alive, make sure your Mac email program isn't using the BinHex scheme for attachments. (Fortunately, no popular Mac email program uses BinHex unless you explicitly tell it to.)

But there's a second, more common problem: Your email program may also compress the attached file so that it takes less time to send and receive. Many Mac email programs compress outgoing files using the StuffIt methodbut few Windows recipients can open StuffIt files.

When sending files from the Mac to Windows, therefore, you should turn off the StuffIt compression option in your email program. (Alternatively, you can download StuffIt Expander for Windows, available at no charge fromwww.stuffit.com, which can open StuffIt attachments.)

---

Note: America Online is a particular problem. When you attach multiple files to a single email message, AOL uses StuffIt compression automatically. When sending files to Windows from AOL, therefore, attach only a single file per email message.Or, use the workaround: Select all the files you want to attach in the Finder. Control-click (or right-click) one of them and choose "Create Archive of [however many] items." After a short delay, your Mac spits out a single .zip filethe Windows file-compression standardwhich you can then attach to your message. Problem solved .

---

5.4.2. Problems Receiving Windows Files

When your Mac receives Windows files by email, the problems aren't so severe. Most email programs, including Mail and Entourage, decompress and decode most file attachments automatically. When they don't, you can drag the downloaded files onto the icon of the free utility program StuffIt Expander, as described on Section 4.11.1. StuffIt Expander can convert most Internet files back into human form.

It's worth noting again, however, that not every Windows file can be opened on a Macintosh, and vice versa. A file whose name ends in .exe , for example, is almost always a double-clickable Windows application that doesn't run on the Mac (at least, not unless you've gone to the expense and trouble of installing a Windows emulator program like Virtual PC). See the table on Section 5.8 for some examples of files that transfer well from Windows to Mac and don't need conversion or adapters of any kind.