It offers a quick view on mobile of "latests posts for all sites" in one click, and many other grouping /filtering options (that miss PostgreSQL website), for users that don't use fat client mailling list system (like me).
This seems even better than nabble www.postgresql-archive.org, that is mobile friendly, and even *even* better as you don't include Ads.
Maybe you will have a better answer if you propose a pure Read-Only mailling list system - without any possibility to reply from your site, - promising NO Ads for ever (and explaining how you get the money for running costs), - ...
Are there any other mobile users here, to vote for this solution (maybe adding other restrictions) ?