Did you get this extension audited by your security team? It sounds insane to me that you’re bypassing IMAP restrictions, with a plug-in that monitors and parses the entire O365 website…
To be fair, it’s the security team’s idiotic position on IMAP that prompted the parent commenter to find a workaround.
It’s like how having super draconian password reset and complexity requirements ends up being less secure because users will start writing their impossible-to-remember passwords on post-it notes.
There’s a big difference between password reset rules, and giving third-parties access to emails and calendar.
There is nothing draconian about restricting IMAP - any app could exfiltrate confidential emails once granted access. It’s a very sane rule to disallow everything except webmail or first party apps.
Of course it does matter! Webmail is quite restricted and optimized for viewing and replying to emails. IMAP is great for that, while also facilitating exporting (exfiltrating) the entire mailbox.
"modern Auth" means OAUTH, so, you aren't giving passwords to the email application.
If you have IMAP on GMail you get two choices, you can admit you're sacrificing security, and they'll mint a random password just for that IMAP application, or you can use OAUTHBEARER. As I understand it if enabled IMAP for Office365 can do OAUTHBEARER.
The nice thing about OAUTH is that it's a natural integration for your multi-factor authentication, which as I understand it doesn't fit well into Kerberos. But to be sure Kerberos is much better than yet another human memorable secret password exchange.
It's the complete opposite, Office365 only supports OAuth with IMAP and is phasing out/has phased out Basic Auth for IMAP. Additionally more often than not organizations are actually running Microsoft Exchange under the hood -- the majority of MS Exchange servers have Basic Auth disabled for IMAP (I believe since 2017 it's been off by default).
That addon got the exact same stringent audit by my security team as did the Firefox web browser that I installed to browse the entire O365 website to begin with.
I interpreted his comment as saying he did not ask permission. Probably he'll be fine as long as nothing he did was explicitly against any rules, even if it is clearly against the spirit of the rules. More likely still, no one will ever find out.
What happened to vetting sources? Beonex is Ben Bucksch, a Mozilla true believer who's been around since before Firefox even existed. The chances that it will suddenly turn into malware is about as likely a distro's coreutils package maintainer going rogue—and far less likely than the revolving door at Mozilla Corp leading to the Firefox product team deciding to do something untoward themselves.
Vetting sources is only basic due diligence. Auditing source code, infrastructure, and data storage is crucial regardless of how “prolific” the author is.