mailto in about:config

I try do what you wont but it's little dificul for me. But I try. I do this fings but it's still not working.

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page.

Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious and if you have a password or other data from that domain that you do not want to lose then make a note of those passwords and bookmarks.

You can't recover from this 'forget' unless you have a backup of the involved files.

It doesn't have any lasting effect, so if you revisit such a 'forgotten' website then data from that website will be saved once again.

You can try a new profile to see if that allows to add the new mail provider via gecko.handlerService.allowRegisterFromDifferentHost = true and the JavaScript code in the Web Console.

navigator.registerProtocolHandler('mailto','https://email.t-online.de/?service=writemail&uri=%s','T-online');

Create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer some files from an existing profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

I found reason why i can't ad to mailto email.tonline.de. To full happy I only ned change two things in configuration. And after when i change that, and visit site I saw ask add to mailto email... ? Thanks for help. I have only one question about syntaks off: navigator.registerProtocolHandler('mailto','https://email.t-online.de/?service=writemail&uri=%s','T-online'); What I need new to knew how create any "navigator..." for any direfent site like email.t-online.de ? Site wich I don't have in default base mailto in firefox.

The do-not-track setting in "Options > Privacy" should have no effect because it only makes Firefox send a specific DNT header via the HTTP request header.
Only a problem with cookies and prefs would have effect.

Hi when, the specific URL to compose a new messages varies from site to site. I can't think of any consistent/reliable way to discover the information, unfortunately.

Ok so wher you found information about this :...https://email.t-online.de/?service=writemail&uri=%s','T-online'); gmail have: https://mail.google.com/mail/?extsrc=mailto&url=%s hotmail difrent compose too. So how can I discover compose wich i need to write in:navigator.registerProtocolHandler('mailto','... ? for any other email login web site

Hi when, the t-online compose URL was "pushed" by the site, so that one was really easy to learn (well, for us it was). When Microsoft changed from Hotmail to Windows Live Mail, we had to search all over the web for the new compose link, and it took a few tries to get it right.

If I had to find one for myself, first, I'd use the mail service support site or submit a question. Presumably they've answered this before. If they didn't help, I would look at how the mail service converts an email link in a message to a new message: is there a compose link associated with that address? If so, great. you just have to replace the email address with %s (and rearrange the parameters so that one is last) and it should have a good chance of working in Firefox. If there's no link, I might be stuck.