Here is a small application I wrote for you to send email with a subject, body text, and a plain text attachment using mailx.
clear
echo "Rob Mail Version 1.0"
echo " "
echo "Mail Utility To Send Email From Unix with Attachment"
echo " "
echo " "
echo "Press Enter To Continue..."
read NOTHING
rm new_mail 2>/dev/null
rm new_attach 2>/dev/null
echo "Enter email address of recipient..."
read TO_EMAIL
echo "To:" $TO_EMAIL > new_mail
echo "Enter Subject of email..."
read EMAIL_SUBJECT
echo "Subject:" $EMAIL_SUBJECT >> new_mail
echo "Mime-Version: 1.0" >> new_mail
echo "Content-Type: text/plain" >> new_mail
echo "Enter Body Text of email..."
read EMAIL_TEXT
echo $EMAIL_TEXT >> new_mail
echo "" >> new_mail
echo "Enter Plain Text File that you want attached..."
read ATTACH_FILE
uuencode $ATTACH_FILE $ATTACH_FILE > new_attach
cat new_attach >> new_mail
mailx -t < new_mail
rm new_mail
rm new_attach