docs: add scratchpad.md for ideas,features,notes

docs/scratchpad.md

@@ -0,0 +1,77 @@
+# Ideas, plans, thoughts on `mailpot`.
+
+It'd be better if this stuff wasn't on an issue tracker like gitea's or 
+github's but committed in the repository.
+
+Discussion about these notes can take place in the mailing list,
+ [`<mailpot-general@meli.delivery>`](https://lists.meli.delivery/list/mailpot-general/).
+
+In no particular order:
+
+**Table of contents**:
+
+* [Possible Postfix integrations](#possible-postfix-integrations)
+* [Setup docker container network with postfix for testing](#setup-docker-container-network-with-postfix-for-testing)
+* [Add NNTP gateways](#add-nntp-gateways)
+* [Add MIME type filter for list owners](#add-mime-type-filter-for-list-owners)
+* [Add `convert_html_to_plaintext` filter](#add-convert_html_to_plaintext-filter)
+* [Use mdoc instead of roff for manpages](#use-mdoc-instead-of-roff-for-manpages)
+* [Add shell completions with `clap`](#add-shell-completions-with-clap)
+* [Make complex database logic and/or complex migrations with user defined functions](#make-complex-database-logic-andor-complex-migrations-with-user-defined-functions)
+* [Implement dtolnay's mailing set concept](#implement-dtolnays-mailing-set-concept)
+
+## Possible Postfix integrations
+
+- local delivery with `postdrop(1)` instead of SMTP
+- log with `postlog(1)`
+- sqlite maps <https://www.postfix.org/SQLITE_README.html>
+
+## Setup docker container network with postfix for testing
+
+Beyond integration tests, we need a real-world testcase: a bunch of user postfixes talking to a mailing list postfix.
+This can be done with a docker setup.
+A simple debian slim image can be used for this.
+Reference for postfix on docker: <https://www.frakkingsweet.com/postfix-in-a-container/>.
+It'd be great if we could use a Rust based solution as well, with something like <https://github.com/fussybeaver/bollard>.
+
+## Add NNTP gateways
+
+TODO
+
+## Add MIME type filter for list owners
+
+TODO
+
+## Add `convert_html_to_plaintext` filter
+
+TODO
+
+## Use mdoc instead of roff for manpages
+
+[`mdoc` reference](https://man.openbsd.org/mdoc.7)
+
+Progress:
+
+- Got ownership of `mdoc` on crates.io.
+- Forked `roff` crate to use as a basis: <https://github.com/epilys/mdoc>
+
+## Add shell completions with `clap`
+
+Probably with <https://docs.rs/clap_complete/latest/clap_complete/>
+
+## Make complex database logic and/or complex migrations with user defined functions
+
+Useful projects:
+
+- <https://github.com/facebookincubator/CG-SQL/tree/main>
+- <https://github.com/epilys/vfsstat.rs>
+
+## Implement dtolnay's mailing set concept
+
+See <https://github.com/dtolnay/mailingset/tree/master>
+
+> A mailing list server that treates mailing lists as sets and allows mail to
+> be sent to the result of set-algebraic expressions on those sets. The union,
+> intersection, and difference operators are supported. Sending mail to a set
+> operation involves specifying a set expression in the local part of the
+> recipient email address.