Okay, fairy nuff.
In that case, I would probably start with writing an SMTP or IMAP proxy first. It will teach you everything you need to know about the protocols, and you can reverse engineer the protocols using a client that already works.
It would give you a tangible project outline, which I believe is often critical to not lose motivation or interest.
If you accept using libraries, there’s the imap crate, the mail_send crate, and samotoo crate that are worth looking at.
I think you’re misguided about the APIs. Gmail supports IMAP and SMTP. Proton supports those too if you run an encryption bridge on your computer. Fastmail supports IMAP/JMAP/SMTP (they invented JMAP to try and innovate).
Email providers most likely must provide SMTP and IMAP due to compatibility requirements with Apple Mail and other clients.
Email is ridiculously complex—the technology is dead simple, but the number of exceptions and (undocumented) rules you need to abide by or risk getting banned by half the internet without being told is nothing to sneeze at.
I should know: I have built multiple support platforms that worked through email (amongst other channels).
You mention wanting to start at the SMTP level, and then building a Qt interface. So you’re going to write an SMTP client, an IMAP/POP3/JMAP client, a storage engine, a user interface, and a better search system, all on your own? You’re describing a gargantuan task.
No offense, but each one of those could be a project on its own. You probably think they’re all simple tasks (they’re not), and that you can follow a few RFCs to get things going (you can’t), and that it’ll be easy to debug (it won’t). Finally, I think you’re underestimating how large people’s email maps get.
Why not write a plugin for Thunderbird that improves the search?
Could you explain what you mean by “full commercial use”?
I would model the part myself, print it myself and check for fit and function. Once the part design and tolerances confirmed, I would then either use a local or remote shop.
Xometry.eu (no affiliation, never used them) appears to be in Europe and outsources to local shops. They have plastic and metal SLS, CNC, sheet metal, and everything else as possibilities. https://xometry.eu/en/direct-metal-laser-sintering/
Another option is to use the Chinese PCB shops. PCBWay has amazing abilities these days: https://www.pcbway.com/rapid-prototyping/manufacture/?type=3&reffercode=TOP
Had this happen to me as well this week after a few months of not using Fusion 360.
Turns out it’s a software update issue. Just close the app every time it fails, and eventually it will manage to update. I have an insanely fast internet connection, so maybe you need to keep it open for a while to download the updates.
If you were to show this comment to someone 10-20 years ago you would have blown their mind:
The irony that u/spez and others keep using landed gentry in the wrong way is hilarious.
Landed gentry bought their “title” (it’s not really a title, more a socio-political category). The first scenario you described, with someone buying the position of moderator… that’s 100% landed gentry. Commoners with wealth would buy a big house and property and then be considered landed gentry. It’s not something that was given to them like peerage (aka nobility).
The reality is that content producers and moderators are closer to cotters–somewhere in between serfs and husbandmen. They don’t own the land (e.g.: subs), but they work it. The only difference is that serfs and husbandmen could derive a profit from their labour, whereas most mods and content producers don’t (as far as I’m aware).
If we keep going with the middle-age titles, u/spez is much closer to a “lord of the manor” than he would care to realise. He owns the land, can choose who works it and who is able to make a profit and how much. He can withdraw that permission at any time, and he amasses vast amounts of wealth based on the work of the people who, effectively, work for him for free.
First sentence on the first hit when searching for “Gmail smtp imap”:
https://developers.google.com/gmail/imap/imap-smtp
What you’re referring to is the fact that GMail has apparently disabled authentication using username + password for SMTP/IMAP. I would assume that application passwords still work fine as a workaround, even if they don’t mention it specifically.