Our company has a software program that allows businesses to manage
their client and prospect data, and to market and sell more
effectively to those people. We have strict policies against spam, we
store opt-in information on all of the leads/customers in their lists,
and we require that customers follow the requirements of CanSpam.

My question relates to our ability to have email delivered
successfully for our clients, to their prospects and customers. I need
the following information:
a.) What are the top 3-5 most widely-used spam-recognition software
programs used by email providers? (For example, spam-assasin...I'm
looking for software that email providers install on their servers to
analyze the content of incoming email messages in an attempt to
recognize spam.)
b.) What are the top 3-5 blacklisting services that are used by email
providers & spam-recognition software to identify sending servers as
spammers?
c.) What are the top 3-5 whitelisting services that we can use to
"pre-legitimize" our email traffic (e.g., bonded sender)?
d.) Please give me information on 2 "email deliverability consultants"
I can contact for ongoing help.

Summary: We need our clients' email delivered. We do not allow
spamming, but we do allow our clients to email their opt-in and client
lists regularly, which will no doubt result in occassional spam
complaints (e.g., the prospect forgets they opted in, has a bad day,
and reports a legitimate email as spam instead of just opting out).

While I believe that a,b, and c above are the correct questions to
ask, my ignorance may keep me from seeing the "real" questions I
should be asking. Despite my ignorance, please help me see what steps
to improve the deliverability of our legitimate email.