imap errors with vpn connections

[Mark Busby]

  I am running Freebsd 6.2-p6 with eGroupWare-1.2.106_1, dovecot-1.0.r2 and mpd-3.18_5.
   
  When I connect from home via vpn to the server then try to check mail thru egroupware I get imap authentication errors. Anyone at work checking their mail will also get the same error,  kill the vpn connection everything works fine.  
   
  I would like to be able to work from home and not block others from checking their mail.
   
  Below are config files and rule sets I have configured.
   
  dovecot.conf
  nothing changed from default config.
   
  ipfw rules
  allow gre from any to x.x.x.x in recv dc0
allow gre from any to any out xmit dc0
allow ip from any to any via ng0
allow ip from any to any via ng1
allow ip from any to any via ng2
allow ip from any to any via ng3
   
  mpd.conf
  default:
                load pptp0
                load pptp1
                load pptp2
pptp0:
                     new -i ng0 pptp0 pptp0
                   set iface disable on-demand
                   set iface enable proxy-arp
                   set iface idle 1800
                   # set bundle disable multilink
                   set link yes acfcomp protocomp
                   set link no pap chap
                   set link enable chap
                   set link keep-alive 10 60
                   set link mtu 1460
                   set ipcp yes vjcomp
                   set ipcp ranges 192.168.1.2/32 192.168.1.50/32
                   set ipcp dns 68.94.156.1
                   set ipcp nbns 192.168.1.2
                   set bundle enable compression
                   set ccp yes mppc
                   set ccp yes mpp-e40
                   set ccp yes mpp-e128
                   set ccp yes mpp-stateless