Correct. It's corporate email. Imagine the amount of contributions that are gated behind stupid email policies because some fossil mailing list client can't handle modern email in the year of our lord 2025
That can't be true. Now, I haven't used Outlook myself, but I've received enough garbage from that godforsaken relic of a time when MS wanted to EEE email to know that that can't be true.
FWIW, I've posted patches to the PG mailing list just fine with GMail. The web app, that is.
OK. Every major corporation uses Outlook and there is no way I can change that so by not accepting its foibles you are artificially stopping interested contributors who would do it on company time and hardware
If by "pathology" you mean "we optimize for the comfort of the people already actively engaged in the project instead of hypothetical future contributors", I don't think this argument is as strong as you think it is.
If anything, this kind of excessive legal and process red tape is much more common in enterprise-driven vs. community-driven open source projects.