Sending email is so quick and easy, it makes most other forms of communication seem like hard work in comparison. The ability to send an accompanying file, in the form of an attachment, extends email's convenience even further.

An attachment can be any type of computer file, from a Microsoft Word document to a photo, from an audio clip to a program. Working with attachments is easy because the process is the same, no matter what sort of file you send.

There are, however, a few traps for the unwary, as well as some commonsense email etiquette rules to observe when using attachments.

Receiving attachments
It's easy to spot an email containing an attachment by the paperclip icon displayed beside it. When you open such an email, you'll see the name and size of the attachment displayed in the Attach(ments) field in the email's header - the same in most other email programs.

Although it is possible to view the contents of an attachment simply by double-clicking it within the email window and choosing Open in the subsequent dialog, that's not a good practice. It's far better to save the attachment to your hard drive first, then open it. Not only does this give you a chance to check the attachment for viruses before opening it, it also gives you a local copy of the file you can modify, while leaving the original attachment untouched.

To save an attachment, double-click it, choose Save, select a location - the Desktop is a handy temporary location - and then click Save once more. Before opening the attachment, run it through your virus scanner to double-check it. Good anti-virus programs should automatically check all incoming attachments for viruses anyway but it pays to be cautious, as email attachments are the primary source of virus infections. In most cases, you can

Once your anti-virus software has given the all clear, double-click the attachment to open it.

Attachment formats
In most cases, that's all there is to viewing attachments. Sometimes, though, you'll find yourself unable to open a particular attachment. That's because in order to open, say, an Excel spreadsheet, you must have a copy of Microsoft Excel on your computer or another program which can handle Excel files. The same goes for other types of files; for each file, you need to have a program capable of handling that file format.

Usually this is no problem, because most people share files in standard formats. For instance, almost all people who use Windows can handle files in the following formats:

• BMP, JPG and GIF graphics
• Microsoft Word DOCs
• TXT text files
• RTF (Rich Text Format) documents
• Adobe Reader (PDF) files
• HTM and HTML Web pages
• MP3 and WAV audio files.

People who use Macs can normally handle that same list of files, with the possible exception of WAV audio, while Linux users can usually work with all but the Word DOCs and WAV files.

If you and your fellow correspondents stick to that list, you should have very few problems sharing files.

What happens if you receive a file created in a program not available on your computer? You can try to open it in another program. Microsoft Word, for example, can open most documents created in WordPerfect (WPD) format.

Otherwise, your best option is to reply to the sender, asking them to resave the document in one of the standard formats and send the new attachment. Almost all programs can save files in a variety of formats, so let the sender know about the problem and suggest an alternative format.

Size and speed
As well as the attachment's format, you need to keep an eye on the size of attachments.

Almost all Internet Service Providers (ISPs) limit the size of individual emails. In some cases, that maximum is as generous as 10 megabytes; in others it's as small as one or two megabytes.

Before you start sending large attachments, check your ISP's limits and check with your recipient to discover their limits, and stick to the lower of the two.

Keep in mind, too, that your recipients may be lumped with slow dial-up connections. A one-megabyte photo attachment takes just a few seconds to transfer on a high-speed link; that same photo will take minutes to ooze into the inbox of someone on a dial-up connection. Unless you know someone who has a high-speed connection, it's bad form to send them large attachments without first checking that they really want or need those attachments.

Zipped attachments
You can sidestep many limitations on both size and speed by using a zip program to compress attachments before you send them. The zip program squeezes the files so they take up less space, making for smaller attachments, and the smaller attachments take less time to deliver.

You and your recipient will both need a zip program installed to handle zipped attachments. Windows XP comes with built-in support for zip files, or you can use a free program such as FreeZip (from members.ozemail.com.au/~nulifetv/freezip) or a commercial program such as WinZip (from www.winzip.com).

Note that zip utilities cannot compress already-compressed file formats, such as JPG images. In some cases, zipping already compressed files will increase their size slightly.

Sending an attachment
Provided you keep the limitations of format and size in mind, sending an attachment is simple:

1. Create an email message as you would normally
2. In the New Message window, click the paperclip icon
3. In the Insert Attachment dialog box, locate the file you wish to attach, click it and click Attach (in Outlook, click Insert)
4. Type the rest of your message and click Send.

An alternative approach is to resize the message window so you can see the rest of your Desktop, locate the file you wish to attach, and then click-and-drag it into the message window.

Useful Site: You'll find a simple list of essential precautions in dealing with attachments at the CERT Coordination Center (www.cert.org/features/green/email-attachments.html).

Tips

• Play it safe
  Never open an attachment from someone you don't know, and never open an attachment from someone you know unless it is expected . Many viruses propagate by sending themselves as attachments, using the addresses of unsuspecting users.

• Easy photo attachments
  Windows XP automates sending photo attachments and will even resize the photos for you. Simply Ctrl+click the photos you wish to send, click E-mail The Selected Items under File And Folder Tasks, and select the appropriate size in the Send Pictures Via E-mail dialog (click Show More Options to see all your choices).

• Don't forget the attachment!
  Few email blunders are more embarrassing than promising to include an attachment and failing to do so. If you use Microsoft Outlook 2000 or 2002, install Attach! (tinyurl.com/29ul3). Attach! scans your email for any mention of an attachment. If it finds a mention but no attachment, it pops up a reminder message asking whether you want to attach a file or send the email without one.

• Slipping through the filters
  Recent versions of Outlook and Outlook Express automatically delete many attachments as being potentially unsafe. This includes program (EXE) files. Always zip EXEs before sending them to evade this filtering.