How to load dummy/fake/mock emails and email folders to a shared IMAP account to test MUA configs?

Summary

How do I create a set of on-demand, mock/dummy/fake emails in numerous IMAP folders? Email content needs to be share-able in a public forum via a commonly-access IMAP-server account (typically for testers/developers trying to debug MUA problems/configurations), with no privacy risks.

I haven't yet found a solution to do this. Unless I can find something (I'm totally looking for suggestions), I'm relegated to writing my own software client. If so, I'd do it in Python, and I'm looking for general pointers on which tools/libraries/methods/approaches I should employ to most-quickly get a first, working prototype.

How should I solve the above?

Details, IMAP-Client Requirements

I want to test various MUA deployments, sharing the same IMAP account between many users/testers/developers (of any MUA) in a public arena. Example: ask on a Notmuch email list: "why is my mbsync/Notmuch config not working? Here's a shared gmail.com account we can collectively use as a common IMAP server to minimize server-side variables and thus collectively help debug stuff." I need to create a variable number of nested IMAP folders with any number and type of emails and email content (the email and attachment content can be "gibberish," so long as the emails can be opened and read by MUAs, and their attachments are "real" enough to be opened by the attachment-file's corresponding application), including any number and size of file attachments. Optimally (but not required for initial versions) I want this IMAP client to be capable of generating GB's of content by creating many thousands of emails and hundreds of nested IMAP folders. Leveraging many or large file attachments will help do this. It's fine to duplicate most of the email content, so long as theres significant variance in Date:, To:, From:, and Subject: headers and email-folder names--all of which can presumably be easily randomized. And I want to generate all this on-demand.

I've pondered trying to non-private-ize existing emails/folders from IMAP accounts I have that serve the above requirements, but it appears just too hard to do that. Too much personal, sensitive information would need to be "converted"/"private-ized."

The only way I see to solve this properly: leverage an IMAP client program that can create emails and email folders on any designated IMAP server/account. Program input can include example (presumably private) email content, number of folders and nesting levels, randomness, date ranges (of emails), etc.

I've not yet found anything that does this. GreenMail appears to setup the IMAP server, but not the IMAP server content--unless I'm overlooking something?