Due to a programming error, over the last year some guest accounts have not had any taglines added to their outgoing emails. It has been our policy since we created FastMail that Guest accounts sending emails
do have taglines added to their emails, and this is even stated in red on the main login screen at http://www.fastmail.fm in the Guest account "features" section. We feel that his is a common, useful and fairly unobtrusive way to promote the FastMail service in exchange for a free account with a minimum of interference to the account user.
This error has now been fixed, and taglines are again being added to outgoing emails from Guest accounts.