Reasonable settings for greyexp and whiteexp

[Sh4d03]

Hi all,

I've got spamd working on my FreeBSD pf gateway, however it seems there 
maybe a few legit senders who are never becoming whitelisted (though 
most are). Until just now my settings were:
passtime: 25
greyexp: 8
whiteexp: 36

I've now just lowered the passtime to 10 and increased the greyexp to 12 
in the hope that I can eliminate the legitimate senders from failing to 
successfully transmit their messages. I was wondering what other people 
have configured for the above settings.

Thanks in advance,

Sh4d03