I know ProtonTeam would see this as one more problem, but in fact it would solve lots of problems that already exist:
1. No need to forward all my other inboxes to protonmail;
2. Since I won't need to forward all my other inboxes, the fake spoofing mail error won't be a problem;
3. Won't need 2 apps in order to use Proton on my Desktop (Thunderbird + Bridge), the client only would be good;

there are a lot of email clients outthere, don't need to dev a new one.
just support the standard protocols to retriever emails from here.

I hope love to have a ProtonMail Desktop Client. It would be much more handy and safe to use than a web browser, no matter which one it is.

I'm oppose this idea. This would strech dev resources thin as it would require development of clients for various operation systems and be kept up to date, especially considering almost daily security problems on the OS level. Keeping it in the browser at least enables them to be focused on one 'system'.

If this is done, please do not do it in Electron. Electron is cancer and has higher than needed overhead. I do not need another Electron app running on my machine.

that defeats the purpose of proton mail doesnt it? how does security work then

As many pointed out porting the web app to desktop via Electron shouldn't be too much of a problem. I doubt however that it will sync with other mailboxes. That wouldn't be needed anyway in my opinion - Thunderbird has already been created.

I also like this idea, conceptually, but would need to see how much this would take away from running the core ProtonMail service before championing it. Like someone noted below, clients like Thunderbird are going independent and might be open to working on something.Two features I have always wanted to see in a mainstream email client are (1) ability to lock/encrypt the database stored on the local machine until the user unlocks the app with a separate password or other form of authentication. Also (2) integrate PGP/GPG and other message encryption mechanisms into the core product, rather than rely on the third-parties for add-ons.

I thought of this too... I would like it, but the only reason I am somewhat opposed, is it increases the size of their software profile for attack. So now instead of just a bridge, an attacker has an entire application to find bugs to exploit. The more features, the more potential weaknesses. Making a good quality and SECURE email client is simply not that simple.

I would love to see this as well. In the meantime, I've been using Thunderbird with Proton Bridge. Since Thunderbird is no longer funded by Mozilla and going independent, maybe they should team up with ProtonMail to develop a new and improved mail client?

I would like to see an email application for Windows.

I think it would be very easy, to built an working protonmail-client using Electron-Frameworks (http://electronjs.org). At the moment,I access Protonmail with an electron-wrapper named "nativefier" and it works very fine.
So the positive facts are, that there is no need of hard programming: you can use the source code from the web app to build an client for your mails.

It shouldn't be too hard to implement. The web version is already quite developed and it should be trivial to integrate that with electron to allow cross platform clients on Windows, Linux and OSX.
A really cool feature would be to save multiple logins for quick switching to different ProtonMail accounts. (work and personal for example)

Or as the previous commenter said, just finish working on protonmail bridge for linux.

My personal opinion is why not both? :)

This would require a lot of effort from the team and would takeover the work from their actual email service. personally I think they should contemplate the acquisition of several deprecated or obsolescent clients of which they're are a few and build upon that making improvements and changes upon that.

They seem to share the same principals with MailPile however that particular client is till going through the beta stage even after this long wait somewhat similarly to ProtonMail actually and OperaMail isn't being used by many and it seems like such a good client, so I think it would be better if they can increase the work force to build upon the client rather than building a client from scratch which is very necessary especially making cross-platform Window-Macintosh-Linux, however it would just annoy the hell out of me if they go through the beta stages with anther line of product.

They couldn't even bother introducing ProtonBridge into Linux, which is so unfair.

make is cross-platform. Linux, MacOS, and Windows. maybe use Electron to develop it.

I agree, what's the hold up on having an app for computers?

I want to view my email from 3rd party software. so you can develop a desktop app or give much information for adding 3rd party software

Please add a Proton Mail app to the windows store so I can access it from my desktop.

I am with Miguel. Using the Web app isn't ideal as there are a number of features that native apps can have that aren't available to the Web app. Please make a Mac app available.

In the GitHub I find many versions of Third-Parts os client for ProtonMail, with UI web.