What are the signature requirements for filing using EFS-Web?

The signature policy of EFS-Web is addressed in detail in the EFS-Web Legal Framework. PDF files submitted using EFS-Web should include either a handwritten signature in compliance with 37 CFR 1.4(d)(1) inserted before scanning the document or converting it to image-based PDF form or an S-signature in compliance with 37 CFR 1.4(d)(2) .  When filing a new application byEFS-Web, a signed transmittal form or a signed application data sheet (ADS) is recommended for identification purposes.  However, a signature is not required to obtain a filing date for a new patent application.  

USPTO FAQ - Questions and Answers (07JAN2007)