I could not add a domain with vpopmail 5.3.23.
I have installed vpopmail 5.3.21 on a test server and upgraded to 5.3.23.
The whole thing worked properly, and I decided to do a new installation
with different compile options.
I deleted the whole thing under /home/vpopmail, cleared all
/var/qmail/users/assign entries (and qmail-newu), cleard all
/var/qmail/control/rcpthosts entries and /var/qmail/virtualdomains
Then I deleted the vpopmail 5.3.23 source tree, and extracted it once
again from the tarball.
Configure, make, make-install suceeded with the compile options like
./configure --enable-clear-passwd=n --enable-logging=y --enable-roaming-users=y
Finally I tried to add a domain, then I got the segmentation fault
after entering the password for postmaster account.
I went over the delete thing again and fell back to 5.3.21 with the same
configure options; everything worked properly.