Hi. Are you wanting to see it as choice for the default webmail provider for mailto: links? See screenshot:

There is a way to do this & Protonmail has made a guide with screenshots for that: https://protonmail.com/support/knowledge-base/set-default-email-handler/ Scroll down to the 3rd section called "Firefox" Note: The option in the screenshot has changed to "Default email application" instead of "Default mail handler" It looks rather easy to do but let me know if you get stuck!

Thank you, but my question relates to the iOS app, which I thought would be clear as I selected an option linking my question to that. What I see at top left of screen in support is a Firefox icon with an apple logo included, but maybe it’s not clear or not visible, depending on browser and operating system combinations? There seems to me to be ever increasing variations in this regard.

I’m afraid your input doesn’t appear to be applicable to iOS, but it does look very useful with regard to the Protonmail/Windows web interface.

Ah thanks for letting me know that it wasn't centric to your iOS app issue. You're totally right. This forum is clearly stated as for the iOS browser but I thought initially you posted in the wrong forum based on your issue. This happens sometimes. Sorry for the mixup!

But then a few minutes later, I dove deeper into your issue on the off chance that it was an iOS issue. Where iOS wasn't behaving properly & wasn't letting you set the default mail handler in Firefox iOS. In the course of that investigation, I did find some interesting answers & a possible workaround. I'd love to know if the workaround works for you & is able to stay enabled.

What I uncovered: In early 2019, Firefox iOS devs were ready to fix this issue & add Protonmail as a default mail handler. Then they discovered something weird. That Protonmail iOS devs disabled this feature internally for security reasons. But by May 2020, Proton's devs talked it over & decided to bring it back in another form. They were testing it in a ProtonMail 1.12.0 Beta build & said they would let us know when it made it to the public release build. It looks like it never made it to the final build or it did, but they didn't inform us of how to use their fix. So progress on fixing this has been stuck since May 2020 sadly.

I also love Protonmail & can't believe this isn't fixed yet. I also have seen a quite few requests in this forum going back a few years asking for its inclusion. I was confused because in every Firefox product you can manually add protocol & application handlers. For mailto:, irc:, tel:, PDFs and almost every file type there is. So it seems like this is a limitation on iOSes side. Maybe Apple blocks adding custom protocol handlers for security reasons?

The workaround found for iOS 14: Source: https://github.com/mozilla-mobile/firefox-ios/issues/7968#issuecomment-786127077 Feb 11, 2021 Work Around iOS 14 allows users to set a default mail service for their device which will also apply to Firefox:

• Open iOS Settings
• Settings > ProtonMail > Default Mail App > "ProtonMail"

Note: This does not close the issue since some users may want to set Default Mail App local to the Firefox iOS App, however this is a working solution for users okay with a global setting.

Ideas in case the workaround doesn't help:

• Find & contact Proton's lead iOS developer Yanfeng Zhang to ask if they have fixed this or if they would like to help Firefox iOS devs fix this. His Github username is zhj4478. I think he is based in San Francisco. Maybe I can try to contact him via Github assuming he still works for ProtonMail.
• Reach out to ProtonMail's support with as much info (links to the Github issues about this problem) as possible & see if they give you a hopeful reply that one of their devs will see your issue & raise it with the other devs.

I've dug deeper down the rabbit hole & found something even MORE surprising. So it looks like ProtonMail's iOS app has been hiding/holding the code for awhile now. Possibly since all the way back in May 2020. But no one had the time to document it & let Firefox iOS devs know that it was ready & working. Someone just made the discovery only 15 days ago! So your timing is quite incredible on this. :)

Everything you read below this point is regarding what happens when you click on mailto: links or email addresses on a webpage.

The bombshell: https://github.com/ProtonMail/ios-mail/issues/27#issuecomment-1096238419 Seoras commented - Apr 12, 2022, 16 days ago Has this been implemented but this issue not marked as resolved? I've just had a look in the code. The App's info.plist has the required CFBundleURLSchemes for protonmail and mailto. AppDelete.swift has implemented func application(_ application: UIApplication, handleOpen url: URL) and handled those two on line 277. This makes me think the code is there...? Installed the app and tested. Yes it does work. Just need to work out the url parameters now. Why is this issue still open and not documented?

https://github.com/ProtonMail/ios-mail/issues/27#issuecomment-1097342511 Seoras commented - Apr 13, 2022, 15 days ago Update: Using the ProtonMail code as a guide and trying various URL configurations I've worked out that the required URL format looks something like this: URL="protonmail://mailto:foobar@foobar.org?subject=SubjectTitleOfEMail&body=MessageBodyFooBar"

So let's watch that page closely to see if the ProtonMail devs do something else to make the URL scheme visible to the public apps that want to use them.