i got the same problem one month ago and still didn't get the time to
write to the mailing list.
From my investigation in the source code results that using mysql
backend for aliases force the vdeluser command to check if the user you are
deleting is a catchall account or not. It search for the default alias
in the valias table and if it not found the default alias for that domain
in the alias table it segfault. I solved this issue, just to test if i
were wrong, adding a valias as this in the valias table:
alias domain valias_line
default foo.bar | /home/vpopmail/bin/vdelivermail '' bounce-no-mailbox
and the vdeluser work correctly.
Now i'm not a C coder and don't know how to solve the issue (other than
make a script that create a default alias
in the valias table for each domain i have taking it from the
.qmail-default file every few minutes).
I hope that vpopmail coders will fix it ASAP because this issue don't
let any of my users to delete users from their domains with qmailadmin
and so on.