[FF] How to add/edit 'link' for mobile email (or other) website

X-notifier 3.3.3 and later

Topic refers to:
extensions.xnotifier.accounts.[HOST#YOUR_ID].link [and set it the URL you want.]

1) Type 'about:config' in the location bar.
2) Look for HOST account with 'enabled' [Right-click] Copy Name
3) [Right-click] New => String
4) [Right-click] => [Paste] and replace 'enabled' with 'link'
5) [Click] OK
6) Enter string value (see below)

• Yahoo mail mobile : http://m.yahoo.com/p/mail
• Gmail mobile : https://mail.google.com/mail/x/
• Gmail html : https://mail.google.com/mail/h/
• Gmail inbox : https://inbox.google.com
• Hotmail mobile: http://m.mail.live.com
• Hotmail [ _?_ ]: http://dub121.mail.live.com

7) [Click] OK
8) Restart Firefox and ENJOY your new mobile version settings.

IF already setting, but you want to change value...
Just [Double-click] on value and input
(Sometime out of date, you might need to search internet, [copy] URL, and [paste] to update it.)

IF you want to remove it or "Forget it" (undo):
1) [Right-click] Reset
2) Restart Firefox  (this will remove your 'about:config' line)

FYI:
X-notifier version 3.3.4 will simply be compatible with Firefox 3.6

Gmail inbox added July 7, 2015. Thanks to Tobwithu.