Hello Birgit,
unfortunately it does not work.
I tried
“phrase1” AND “phrase2”
‘phrase1’ AND 'phrase2’
phrase1 AND phrase2
But the result was empty.
standalone phrase1
standalone phrase2
works fine.
Maybe you use a different egroupware version?
I use the community version 1.8.004.20130831
Greetings
Manfred