getting emails into inbox

[Al Zick]

Hi,

We have been using the same mail server for a long time with the same  
IP. It relays the email for several webservers and of course all of  
our email. Yet, lately (maybe the last month or so) I have been  
getting a lot of complaints about their emails not being delivered  
and sending the same email via yahoo it gets through. I have been  
considering sending the email to google for relay, but is this even  
an option? Do we need to implement outgoing spam filtering?

Thanks,
Al