Thanks for the link to that test site - I didn't know about that. As for K-9: Apart from doing calls I really just use my phone for mails and K-9 isn't the rig

Thanks for the link to that test site - I didn't know about that. As for K-9: Apart from doing calls I really just use my phone for mails and K-9 isn't the right choice for me, sadly. I would really love to use an open client, but while I can compromise on quite a bit (trying to migrate to a CM without any GApps is next on the list), a decent mail client is mandatory. (Incidentally that's the reason why I can't use Fx OS so far, the situation is worse over there) Interesting enough: Testing K-9 and Boxer on that site I get one violation in each. Boxer with a 'Link Prefetch' as you said, K-9 with a 'Meta refresh'