"... all of a sudden ?"

That has been in the works since Firefox 39, over a year ago! The first "deadline" was Firefox 42, then it was 43; then it was "pushed back" a few more times.

https://support.mozilla.org/en-US/kb/add-on-signing-in-firefox

There's been a message in the Add-ons Manager for each extension that "can't be verified for use in Firefox" since Firefox 41 - so users have had "fair warning" for close to a year now.

My advice is to look for a similar add-on that is signed or wait until a Bug is resolved with the "unbranded builds". https://wiki.mozilla.org/Addons/Extension_Signing#Unbranded_Builds

I thought Microsoft were the only controlling company.

Nope, Apple and Google Chrome along with Mozilla all care enough about their users to have minimum requirements for add-ons / apps that are allowed to be installed in their web browsers.

What extension is it? You can copy/paste its name and its "unique ID" from this page:

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

Scroll down to the Extensions heading and the details are in the table that follows.

If it's impossible to find a good substitute, you can postpone the day of reckoning by about another nine months by using the ESR version of Firefox 45. More on that if needed.

1 Well up until version 48 we were allowed to use "unsigned" add-ons by amending the config file and I haven't noticed any adverse affects from using the add-on concerned on my system so I had just hoped I could continue. It's not exactly a big deal but I just thought I'd give my point of view, - I'll think twice in future

2 Thanks for the info, I've rolled back to version 47.1 and tried to contact the add-on creator to see if it can be signed though I'm not holding out much hope

Could you possible also include a post with the plain text info from about:support There is an e10s experiment in version 48 that may also be affecting web addons.

This is the information from the extension list

Get Mail Plus 3.4.10 true getmail@webdesigns.ms11.net

Were you using it for an external mail program or a webmail site?

There are some more general extensions that can launch an external program. I haven't tested these myself:

• Custom Buttons - has a community support site for detailed help
• External Application Buttons 2 - don't know how much help there is

For webmail sites, there are a variety of site-specific extensions, or to just go there, a bookmark should do the job.

I was just using it as a link to microsoft outlook as it can be installed onto the firefox toolbar. I don't have too much space left on my taskbar to pin outlook to it so it was handy to have the shortcut in firefox. Shame it's an older add-on which isn't being developed so it isn't safe to use now!

I'll check out those links and I appreciate the help and your time. Of course it's not a major issue but you get a settled system and you hope you can keep it that way

Those links have been a great help, with either of those add-ons it's easy to create a shortcut tab with the programme icon, for any programme - in my case, microsoft outlook. It displays in the firefox toolbar - job done!!!

thanks for your time and help

cheers!

OOPs I looked at an old copy of the question that was still shown as unanswered.

Sorry, Mozilla will be aware this change is going to hurt some users.

The problem is not only that old addons may not work but that addons may be used as a method of attacking your computer and your data. A malicious emaiil addon may be able to do things like scan your emails for passwords and pass that to some third party.

The signing criteria is only a check that addons are safe and secure, but the person developing or hosting the addon needs to get it signed, Once signed you know the addon is safe to use.

It is possible to use unsigned addon, but that's not really intended for the average end user, more for developers testing out addons, because it involves using none standard versions of Firefox.

There are hundreds of email related addons

• Search link

Hopefully you will be able to find something similar or better that is signed and will work for you.

What is the addon you use at the moment ? Did you find a suitable replacement ? & if so what is that?

The signing only affects Extensions to be specific and not all other Addons also like Plugins, Themes (complete and image), search engines, language packs, dictionaries.

I solved this by installing quick file launcher and pointed it to my email exe and put this on my toolbar. Works just like get-mail.