So, it's called fakemail but there is a real SMTP server in there. Attachments should work fine. Getting the web app to create SMTP accounts was quite tricky, I'm sure there are better ways but I ended up implementing the unix crypt() algorithm in C#.
Server is holding up fine so far (there was a rate-limiting bug which brought the site down yesterday). Logs show 37K unique IPs have accessed it since yesterday, and it seems to be using about 1% of the CPU (it's on a free VM in the Oracle Cloud).
There is a whole API sitting behind the web page, including proper authentication, but the frontend is very much a MVP.
Very few actual emails have been sent to it, so I'd love it if people could actually send stuff. There are a bunch of websites that can be used to send test mails, e.g.
Most people these days are using a service provider for SMTP in production, so it isn't really possible to keep your prod and test configs in sync.
I do agree about using testing everything real tools, which is why this (fakemail) uses OpenSMTPD as the mail server.
All the work is in configuring it (similar complexity to your postfix configuration by the looks of it), interfacing to it, and deploying it (currently using ansible but will probably dockerize it).
The fact that no emails can get through to a real recipient is a feature.
The idea is that, in a a test environment, we should not actually deliver the mails to the recipient, instead making them available on a web page (or through an API).
a) impersonate the identities of your users and b) decrypt the SSL traffic of your users
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