Sometimes the simplest of things are not actually easy to understand and I think this is my current roadblock with email. I am ready to begin doing email on my Ubuntu Budgie MacBookPro. I really want to do this right the first time and I am stuck on step one because I can’t wrap my brain around the lingo (provider, client, etc) and/or the way email actually functions. I want a reasonably private email (anything would be an improvement over my current gmail) so I’m thinking a freebie Proton. I want to receive emails on my laptop and store/organize them there (not have to access via web and store them there). I am so brainwashed by Apple that I just cannot think beyond the way my gmail magically appears in my Mail program. Can anyone explain it to me like I’m a third grader? I won’t be insulted, haha!
Hey, @JK!
First, let’s clear some lingo for you.
Provider is the service/company that offers you goods, like an email account, which it hosts on its own servers. Example, Google with its GMail service.
Client is an application that hooks up to the Provider’s services and utilizes them without having to use a browser. Example, Thunderbird email client, which downloads and keeps your emails locally (and you can also send from your local system).
To utilize an email client with Proton, you will need to download and install their Bridge Software.
https://protonmail.com/bridge/download
Since you have Ubuntu Budgie, you will need to download the DEB file for Linux. Once it downloads, double click on it to bring up the Software Center that will allow you to install it.
When you run it, you will need to login to your Proton account, so that it gets the data from it. Once done, then it will offer you the details on what settings to manually put on your Thunderbird email client.
Next, run Thunderbird. If you do not have it installed, open up your software center and search for Thunderbird. Install it and then run it.
When you first run Thunderbird, it will ask you to put in the data for a new account. Write down your name and email address, and then select Manual Configuration. That’s because of the Proton Bridge.
Open up Proton Bridge and look at the email client settings. Copy them to the Thunderbird’s panel, select “Test” and once everything checks out, hit OK. Then, you’ll be done!
The reason Proton has a Bridge app (it’s the only one I know of) is because it encrypts your email directly on your computer before it sends the message out. It also acts as a decryption tool when you receive the emails. From there on, all emails that download to your Thunderbird have a local copy on your system. 
Once again, Vasileios, your explanation cuts right through the fog. Thanks immensely for the step by step explanation which distilled the process and allowed me to wrap my brain around it. Now I have an understanding AND a clear path forward. This is exactly the kind of answer I had hoped to find here. I’m sure I’m not the only one confused by email, so hopefully this thread will help others, too. Thanks!
You are most welcome, @JK! And you are correct. We do our best to be as comprehensive as we can, so that we build a good online database for issues others may encounter. 