Allow inbound email only for a specific Domain for SMTP VS- iRule?

Dear Kevin,

Thank you very much. Do you think following, the smaller version would work to achieve the requirement? I made it before I received this one.

when CLIENT_ACCEPTED {
    set cto ""
    set cdata ""
}   
when CLIENT_DATA {
set cdata [TCP::payload]

    if { [string match -nocase "RCPT TO:*" $cdata] } {
        set cto [TCP::payload]
        set fromaddr [regsub -all \[\\r\\n\\s\] $cto ""]
        set toaddrs [findstr $toaddrs ":" 1]
        set todomain [findstr $toaddrs "@" 1]

   if { [ class match $todomain equals "MailAddrList" ] } {
            log local0. "Email Accept based on the receipeint email address"
        TCP::payload replace 0 0 $cto
        TCP::release
        TCP::collect
        else {
        }
                drop }
}
}