I mainly send from my own mail server, too. If I worry that email to a cold gmail contact will end in spam, I use a simple fallback strategy. I have gmail set

I mainly send from my own mail server, too. If I worry that email to a cold gmail contact will end in spam, I use a simple fallback strategy. I have gmail setup to send as an alternate email address, so it appears to come from my server's domain. The contact will certainly see gmail to gmail email, and if they reply, my email address goes into their (effective) contact list.