I could not figure out why only MySQL can now be used for valias only, so I just created a patch to 5.4.13 to remove this check (I still use valias in the form of .qmail files). Patch attached.
diff -uPr vpopmail-5.4.13.orig/configure vpopmail-5.4.13/configure --- vpopmail-5.4.13.orig/configure 2005-09-17 00:37:34.000000000 +0100 +++ vpopmail-5.4.13/configure 2005-10-21 13:45:43.000000000 +0100 @@ -6584,19 +6584,19 @@ 1*|y*|Y*) echo "$as_me:$LINENO: result: yes" >&5 echo "${ECHO_T}yes" >&6 - if test "$USE_MYSQL" != 1 - then - { { echo "$as_me:$LINENO: error: valias is only supported in the MySQL authentication module" >&5 -echo "$as_me: error: valias is only supported in the MySQL authentication module" >&2;} - { (exit 1); exit 1; }; } - else +# if test "$USE_MYSQL" != 1 +# then +# { { echo "$as_me:$LINENO: error: valias is only supported in the MySQL authentication module" >&5 +#echo "$as_me: error: valias is only supported in the MySQL authentication module" >&2;} +# { (exit 1); exit 1; }; } +# else VALIAS=1 cat >>confdefs.h <<_ACEOF #define VALIAS $VALIAS _ACEOF - fi +# fi ;; *) echo "$as_me:$LINENO: result: no" >&5