Postful

Send photos by including them as attachments.
Send PDF and Office documents.
Send letters just by including a name and mailing address in the subject line.
Create special e-mail addresses for frequent contacts so that you don't have to type in their address each time.
Send to an entire mailing list with a single e-mail.
Full color, high quality printing.
Use rich text formatting.
Keep records of all letters you send.
Send to military APO and FPO addresses as easily as any other address.
Send letters internationally (50 countries in place, more to come).