Michael Ludwig schrieb am 06.02.2013 um 21:24 (+0100):

> PS and not specific to this topic:
>
> I don't know what »User-Agent: eGroups-EW/0.82« is but it doesn't
> appear to honor Internet Mail Message IDs, omitting the »References«
> header, thus breaking threads, which negatively affects list
> readability.

Looks like that's the Yahoo web interface. Just checked my mail folder,
the web interface used to work okay, even with the version string quoted
above. So probably just a bug that'll hopefully get fixed soon.