A 'Signature Line' comes at the end of an email right below the sender's sign-off Creating a company-wide starndard strengthens branding efforts. When an email is forwarded onto another person(s), the signature follows with the original message. As stated earlier, Hotmail.com's signature line has become their successful marketing campaign.
Signature lines can be as simple as the company name and web address. For marketing benefits, add a tagline (strapline) with contact information. Logo imaging can also be added if the 'weight' of the image is low and pixel size is small. Emails shouldn't weigh down a recipient's email server. Additionally, images may cause emails not to be received. We'd recommend to use of colored text instead of logo images to help.