SMTP domain Whitelist Allow SMTP request based on MAIL FROM on serverside

Hello iRule experts,

I am an irule beginner and I need some help.I have a datagroupe that contains more than 200 domain . I need route mail based on the domain found in the FROM header . My irule must verify if this domain has been properly Whitelisted by checking the datagroupe . My Irule Work when I'm using SMTP in cleartext without starttls activated on smtps profil . But with SMTP STARTTLS activated it's not work .So I'm want to check the mail from on Serverside because it using SMTP without Starttls .

CLIENT-----:Port25(allow Starttls)F5--->SMTP(ClearText):Port25-->SERVER

Here is my Irule that check MAIL FROM on CLIENT SIDE : Only Work if I use SMTP without Starttls configured on SMTPS profile

when CLIENT_ACCEPTED {
    set cto ""
    set cdata ""
    log local0. "Connexion de [IP::remote_addr]"
    LB::connect
    TCP::collect
    set hsl [HSL::open -proto UDP -pool splunk.lab.local]
    set client_ip [IP::client_addr]
}
  when CLIENT_DATA {
    log local0. "CLIENT_DATA"
    set cdata [TCP::payload]
    log local0. "cdata : $cdata"
    set hsl [HSL::open -proto UDP -pool splunk.lab.local]
    if { [string match -nocase "MAIL FROM:*" $cdata] } {
        log local0. "domaine : $cdata"
        set fromaddr [regsub -all \[\\r\\n\\s\] $cdata ""]
        log local0. "domaine : $fromaddr"
        set fromaddr [findstr $fromaddr ":" 1]
        log local0. "domaine : $fromaddr"
                set fromdomain [findstr $fromaddr "@" 1]
                log local0. "domaine : $fromdomain"

        if { [ class match [string tolower $fromdomain] contains "MailAddrList2" ] } {
            TCP::payload replace 0 0 $cto
            pool /Common/SMTP_POOL
            log local0. "Email Accept based on the recipient email address"
            log local0.info "domaine, $fromdomain, accepted , real client ip is : $client_ip"
            HSL::send $hsl "<190> domaine, $fromdomain , accepted, real client ip is : $client_ip \n"
            HSL::send $cdata "<190>domaine, $fromdomain , accepted"

                               } else {
                                   reject
            log local0. "Domain not allowed please contact your administrator "
            HSL::send $hsl "<190> domaine, $fromdomain , not accepted, real client ip is : $client_ip \n"


                               }
    }
    TCP::release
    TCP::collect
}
when SERVER_CONNECTED {
    log local0. "Connexion au serveur"
    TCP::collect
}
when SERVER_DATA {
    log local0. "sdata : [TCP::payload]"
    TCP::release
    `text`
    TCP::collect
}

Many thanks in advance

Hermann