Preserving Client IP address for SMTP traffic

Hi,

 

 

We have a requirement to loadbalance two SMTP servers via F5 load balancers, Since we are using SNAT the real client IP is not visible to the smtp servers. Is there any option avaialble for the servers to see the client ip. I have earlier done a similar thing for HTTP traffic using Xforwarded-for, do you have something similar to smtp.

 

 

Thanks,

 

Venkat