Netauth ini setting changes

For the host domain "a.com" (labeled H) and suffix based virtual domain "b.com" (labeled V):
  vdomain b /suffix b.com \dmail\in

dmail.conf netauth.ini (pre 4.2e) new style netauth.ini (5.0a+) drop file authent name login
host_domain a.com
vdomain b /bsuffix b.com \dmail\in
authent_domain false
drop_prefix true
domain a.com
prefix NULL

vhost b.com
domain b.com
prefix b_
suffix /bsuffix
vend

domain a.com
authent_domain false
drop_prefix true

vhost b.com
domain b.com
prefix b_
suffix /bsuffix
vend
H <user> <user> <user>
V b_<user> b_<user> <user>/bsuffix
host_domain a.com
vdomain b /bsuffix b.com \dmail\in
authent_domain true
drop_prefix true
domain a.com

vhost b.com
domain b.com
user_create_prefix false
prefix b_
suffix /bsuffix
vend
domain a.com
authent_domain true
drop_prefix true

vhost b.com
domain b.com
prefix b_
suffix /bsuffix
vend
H <user> <user>@a.com <user>
V b_<user> <user>@b.com <user>/bsuffix
host_domain a.com
vdomain b /bsuffix b.com \dmail\in\b
authent_domain false
drop_prefix false
domain a.com
prefix NULL

vhost b.com
domain b.com
prefix b_
suffix /bsuffix
vend

Doesn't work!!

domain a.com
authent_domain false
drop_prefix false

vhost b.com
domain b.com
prefix b_
suffix /bsuffix
vend

H <user> <user> <user>
V <user> b_<user> <user>/bsuffix
host_domain a.com
vdomain b /bsuffix b.com \dmail\in\b
authent_domain true
drop_prefix false
domain a.com

vhost b.com
domain b.com
suffix /bsuffix
vend
domain a.com
authent_domain true
drop_prefix false

vhost b.com
domain b.com
suffix /bsuffix
vend
H <user> <user>@a.com <user>
V <user> <user>@b.com <user>/bsuffix