Should we attach resume file to job application emails?

When job seeker applies to your job posting, PostJobFree emails you job seeker's application.
We include job seeker's resume into body of that email as a plain text.

Some recruiters asked me if PostJobFree can include resume as an email attachment.
We can make that change, but only if many recruiters would like to get resume in form of attachment.

Please let me know what you think about it:

1) Would you like to receive resume as a text inside of application email body or as a file attachment?

2) What resume file format would you prefer as an attachment?

• pdf
• doc
• docx
• html
• txt

3) Would you like to receive resume in the same file format that job seeker uploaded it in?
Possible advantages:
- Original resume contains formatting (headers, fonts, tables, etc).
Possible disadvantages:
- Resume extension and formatting would be different from job seeker to job seeker.
- Some of originally uploaded resumes may contain viruses (not very likely but may happen).
- Attachment size may be quite large.

Please let me know what you think in comments below or email to webmaster@postjobfree.com

Update:
Based on feedback I'm receiving by email it looks like most recruiters prefer PDF attachment.
DOC/DOCX is also popular.
Some recruiters are asking me to keep sending resume as a plain text inside email body.