You found the perfect job on the Internet - or at least one that will pay the bills and isn't too unpalatable. The employer or recruiter provides an email address and instructs you to paste your resume right into the body of the email. Your resume, painstakingly prepared, delicately balanced with hanging indents, bold and italics, neatly aligned columns - will probably be immediately bounced if you try to file attach it.
Programs scan the text for keywords stipulated in the job description.
On finding resumes with the required percentage of keywords, the program flags those for further review - all based on how many keywords match the job requirements. This is especially so for technical positions. Another reason for immediate rejection of file-attached rather than pasted in resumes is that not all organizations use your particular word processing program, and some email programs garble the attachment. Direct marketing, and you are marketing yourself, has a percent of return based on targeted volume. Let Notepad wrap the paragraphs rather than inserting a return at the end of each line.