UTM 9 How to send email from external with SMTP proxy on and without authenticated relaying

Hi,

i'll try to explain the best i can.

So i have an internal mailsever for family and friends with a couple of domains.

the internal mailserver and mail domains are protected via the UTM 9 SMTP proxy.

works fine.

I have a small /29 IP V4  ip range for SSL , Mail and Web so those servers have a singel IPv4 address.

The problem is, if someone is extern and try to send mail via whatever iphone, laptop u name it, the SMTP proxy takes the connection and deny's it.

the only thing i get this working ist via Allow authenticated relaying in the relay Tab .

Edit: The SMTP Proxy does not run in transparent mode

But i think that is not the best solution, because i get  a huhge amount of connection testing because of the open authenticated relaying.

Any hints ?

Thanks !