I once worked for a company where a lot of the senior management (and, more importantly, their secretaries) still thought that internal communication revolved around printed memos. I often received email messages whose entire content was: "See enclosed memo." So I dutifully opened the attached documents in Word, where I invariably found a paragraph or two of text in the company's standard memo template that could just as easily have been typed (or pasted) directly into the email message. This backward approach to communication annoyed me mightily, because the senders' failure to use email properly forced everyone else to jump through hoops to read a simple message.
Enlightened email users (such as, I'm sure, most TidBITS readers) use attachments only when they add something one can't convey in the body of a message. But even our best efforts to use attachments wisely can be undone by uncooperative email programs. Apple Mail, despite its general ease of use, sometimes handles outgoing attachments in unexpected ways. You can make sure the vast majority of your attachments arrive intact for the vast majority of your recipients by following some simple guidelines, which I've excerpted from my latest ebook, "Take Control of Email with Apple Mail."
Always Include File Extensions -- Filename extensions never hurt, and they often help (even when your recipient is a Mac user). To make sure an individual file has an extension, select it in the Finder, choose File > Get Info, and look in the Name & Extension section. As far as Mail is concerned, it doesn't matter if a particular file has the Hide Extension option checked; as long as the extension exists, it comes through on the recipient's end. To save yourself the bother of checking each file (at the expense of slightly less beautiful file names), choose Finder > Preferences, click the Advanced button in the toolbar, and select the Show All File Extensions checkbox. That way you'll always know at a glance whether a file has an extension.
Always Use Windows-Friendly Attachments -- Sending attachments in "Windows friendly" format usually makes them friendlier for Macs too. The Windows Friendly Attachments feature has nothing to do with extensions and does not add them for you. So, what does it do?
By default, Mail assumes your recipient is also a Mac user and therefore includes the resource forks (if any) of attached files. Normally a Mac user sees such attachments as a single file, whereas a Windows user sees two individual files - one containing the data fork of the file and the other containing the resource fork.
When you choose "Windows Friendly" attachments, Mail strips the resource fork so that Windows users receive just one file, not two (one of which would be unusable anyway). In most cases - at least for files created with modern applications - all the crucial parts of files are in the data fork; as long as the filename has the correct extension and they have an appropriate application, Windows users can open the file.
The term "Windows Friendly" seems to imply that using this option makes your attachments "Mac Unfriendly." Mail's documentation reinforces this worry by stating that Mac users may be unable to open files correctly if the Windows Friendly option is used. But in practice, just the opposite is frequently true. The Mac version of Eudora, for example, sometimes cannot decode perfectly ordinary Mac files, such as Word documents, if they were sent without using the Windows Friendly setting. In other words, a wiser design might have been to make "Windows Friendly" the default behavior, with an option to make attachments "Mac Friendly" on those rare occasions when you truly must.
To tell Mail to use Windows Friendly encoding for all new messages, choose Edit > Attachments > Always Send Windows Friendly Attachments. (Although this command appears on a menu, it's actually saved as a preference.) Oddly, this command is disabled when composing a new message.
You can also toggle Windows friendliness for individual messages: When you attach a file using the Attach button on the toolbar or by choosing File > Attach File (Command-Shift-A), notice the checkbox at the bottom, Use Windows Friendly Attachments. If it's selected, all the attachments for this particular message are sent in Windows Friendly format. Unfortunately, Mail offers no convenient way to toggle Windows friendliness for attachments added to your message by drag & drop or copy & paste.
When a Problem Comes Along, You Must Zip It -- If file extensions and Windows friendliness still result in attachments the recipient can't read, try compressing them (the files, not the recipients). Zipping covers a multitude of sins by wrapping up one or more files - including resource forks, if any - in a compact, cross-platform-compatible package. Under Panther, you can compress a file or folder in the Finder (in Windows-friendly Zip format) by selecting it and choosing File > Create Archive of <filename>. Of course, StuffIt Deluxe and StuffIt Standard Edition can also create the protective Zip or StuffIt archives as well.
Sending Graphical Attachments -- When you attach a graphical image to your message, the recipient of your message sees the image inline (that is, in the body of the message) if her email client supports inline display. ("Take Control of Email with Apple Mail" contains a table listing the capabilities of popular Mac and PC email clients.) If a client does not support inline display (or the recipient has turned off the inline display option), the file appears as an attachment that must be opened in a separate program.
On the one hand, an inline image is easier for the recipient to see - all she has to do is look at it. On the other hand, inline images can be frustrating to scroll through. If you do not wish to send a graphical image inline, you must compress the file before attaching it - Mail, sadly, lacks a built-in compression option, though fortunately for Panther users, the Finder offers Zip compression without requiring a separate application.
Note that when you compose a new message, Mail always shows attachments in the body of your message. You can manually drag them somewhere else, but many email clients display all attachments in a separate list, regardless of where you place them in the message body.
If you paste an image into a message or drag & drop an image from another window (say, a Web browser), Mail converts the raw image data to an attachment in TIFF format. On the other hand, if you drag & drop the icon of an image file (or use the Attach button to locate the file using the file browser), Mail leaves the attached image in its original format. This difference is significant, because although most email clients can display JPEG images just fine, support for TIFF - especially in non-Mac email clients - is less common. If possible, I suggest attaching image files as opposed to pasting or dragging in raw image data.
Take Control of Email with Apple Mail -- As much as I like Mail, it has quite a few other quirks and frustrations - ranging from misleading error messages to seemingly missing features. After experiencing many of these problems myself and reading literally thousands of reports of others struggling with the same things, I set out to determine what's really going on behind the scenes. In my 89-page "Take Control of Email with Apple Mail" ebook, I explain why Mail works (or doesn't work) the way it does and how you can solve many of the most common Mail problems. Even if Mail is working perfectly well for you, you'll learn how to use it more effectively. "Take Control of Email with Apple Mail" costs $10, or you can purchase it along with "Take Control of Spam with Apple Mail" (ordinarily $5) for a total of $12.50. As with all Take Control ebooks, purchasers are entitled to receive all minor updates for free.
[Joe Kissell is a San Francisco-based writer, consultant, and Mac developer who kicked off the Take Control series with the best-selling "Take Control of Upgrading to Panther." When not solving Mac problems, he gives guided tours of the rest of the world on his Interesting Thing of the Day Web site.]