pf and Microsoft Exchange IMAPS

[Raphael GRUNDRICH]

Hello,

I'm trying to redirected outside traffic to internal Exchange Server using 
IMAPS protocol :

 rdr on $ext_if proto tcp from any to any port 993 -> 192.168.1.1
 pass in quick on $ext_if \
        proto tcp \
        from any to 192.168.1.15 port imaps flags S/SA synproxy state

Outlook client seem to pass the firewall but after that it hung on "Protection 
..". Does anyone here have manage to get PF and IMAPS Protocol from Exchange to 
work  ?

thanks,

Regards