Hi R.1C, You will need to get help with your WebMail service. See - Using webmail services https://support.mozilla.org/en-US/kb/change-program-used-open-email-links#w_using-webmail-services

There is other relevant information in that same article.

Hi RobertJ,

Thank you for your time and trouble in researching this problem for me.

I have read the article but I think it will need a few more sessions studying it to make sense to me!

I might - stress 'might' - get there eventually!

Thank you very much.

Ray

Hi Ray, I don't know whether you've ever seen it before, but sometimes when you are viewing your email inbox, Firefox will show an extra bar/button in the toolbar area to add the site as a mailto "application." I'll insert an example below for reference. Clicking that button will configure the compose URL for you so you don't need an add-on. However, I don't know whether your email site has that.

Hi jscher2000,

Thank you for going to all this trouble to try to help.

Unfortunately, I have never seen in Firefox what you have researched.

But I am grateful for your trying to help.

Thanks.

Ray

Thanks to everyone for your help.

Ray