The recipient needs to use a mailer that accepts attachments and have software that can load the attached file. It wouldn't do any good to send a WordPerfect file to a Word user, for example, because they might not be able to open the file. Regular text email messages cannot contain viruses, but attachments can. Recent scares due to attachment viruses have made people cautious about opening attachments. Saving and scanning the attachments with anti-virus software first is a prudent step, but it adds even more steps to the process.
Most attachments become rather large files to send through e- mail.
Sending or receiving a file that contains an attachment can take a long time for someone who uses a modem to connect to the Internet. If you are using an attachment to send text from an existing file, importing or copying the text into an email message is a better option. That takes very little effort on your part. It makes life much easier for the recipient. And the chances of your message being received and read are much better.