Hey, Please contact your email website for more details, i have some guide for some popular email site, here are those:

• Gmail: https://support.google.com/mail/answer/8395?hl=en
• Hotmail/Outlook: http://www.wikihow.com/Create-an-Email-Signature-in-Hotmail
• Yahoo: http://help.yahoo.com/tutorials/mmail/mmail/mm_customize3.html
• Rediff: http://support.rediff.com/cgi-bin/support/printdetail.cgi?id=mail_607.htm
• Sify: http://mailhelp.sify.com/rich-text-signatures/

THanks

Thanks for the answer Swarnava, but I need also to configue my signature in the corporate Exchange mail account.

Hello,

Firefox OS doesn't currently support email signatures. This feature will be coming in a future version of Firefox OS. Possibly in v1.2.

There is a bug report here where you can keep track of the progress of the work being done: Bug 847168

I hope this helps.