If an employer indicates that he or she would like a resume e-mailed,
then e-mail one with a cover letter. However, it does not hurt
to follow up with a hard copy in the mail as hard copies are often
more attractive and reader-friendly than a text resume. Many employers
do not want to receive resumes through an attachment as they may
contain viruses. It is better to format a text resume to fit within
the e-mail itself.
Few job seekers send resumes and cover letters through the mail.
To make yor stand out, this "old-fashioned" way may
be helpful.
Some helpful links: