WASI has been in Preview1 for a couple of years now, indeed. However, Preview2 is well underway and the initial implementation is scheduled to land in wasmtime this June.
without these we can't compile our favorite apps in our favorite languages
lets help get these into preview2 so that WASIX is not needed anymore but until then the community needs an interim solution that has long term support - that is WASIX's complimentary goal.
An email sandboxing and testing application called MailSpons: https://mailspons.com/
Primarily, it allows developers to set up fake inboxes for their local development environments.
The only thing you have to do is change the SMTP settings of your local environment and then all mails will be caught by MailSpons.
The next step is to automate end-to-end testing of applications by reading the sent emails via the API. I am currently writing the documentation for that.
Please don't be put off by the homepage. I, a developer, "designed" it ;)