Version:            (using KDE KDE 3.3.0)
Installed from:    SuSE RPMs
OS:                Linux

Symptom: the Address Selection dialog (opened with the ... button on To and CC field) is exploded vertically; i.e. the list boxes run down to the border of the dialog no matter how high you stretch it, and no buttons appear on the dialog (because they are positioned in the center of or below the infinitely high list boxes).
The culprit turned out to be the Recent Addresses value in kmailrc.  It contained one of the vcard entries you get pasting addresses from Address Book since KDE 3.2(*).  I think it's a reasonable thing to try to send an e-mail with these strange vcard entries in the to field.  The sending fails, but the entries are still inserted in Recent Addresses, and mess up the Address Selection dialog forever.

(*) if you copy contacts in Address Book and paste them in a To: or CC: field, KDE 3.1 and earlier would paste valid e-mail addresses; KDE 3.2 pastes vcard gibberish. This is described in another bug report (that I found in a minute the first time, and couldn't find back after an hour now) and attributed to a change in the KDE clipboard.