When inserting e-mail address, the autocompletion does not work. If I switch via right button in Text Completion to "Automatic" then it somewhat works. Anyway, inserting more addresses mean always to switch in Text Completion to "Automatic". Previously working "Dropdown List" does not work any more.
Even "Search for Addresses in Directory" does no work, while commandline ldapsearch works fine.
Fixed in last 5.20.x and master
*** Bug 458042 has been marked as a duplicate of this bug. ***
Was going to reopen, but realized that the bug was reported on the same version I just switched to... so I guess I'll have to wait for the fix to land on my desktop...