Welcome to the forum.
Sorry for the delay getting back to you, I was neck deep in some code that Nick wrote...yeah, the same Nick that replied to you yesterday... Small world.... Wouldn't want to paint it.....
Anyway, here we go.......
The DNS address is the Domain Name Server address. Its the IP address of the computer/server that resolves domain names to IP address's. In other words, when you put in opto22.com, that DNS server converts the nice human readable name into an IP address.
You can do it as Nick described and use the DNS IP address that's in your computer, or you can just belt in 188.8.131.52
This is Googles DNS server. Or, do as I do, use the Open DNS server IP address of 184.108.40.206
All three will work exactly the same.
The one thing that HAS to be right for any of the DNS stuff to work is the gateway address.
The gateway is the IP address of the computer that is the onramp to the internet in your company.
At our homes, the gateway is the router, most often 192.168.1.1, so everything points to that, but you cant just use any IP address for it, it has to be the right on for the network the PAC controller is on.
If its on the same network as your PC, then use Nicks method, open up a dos prompt (cmd in the windows search bar) and use the command he shows. This will give you the gateway IP for your PC, use this IP address in the PAC Controller (entered using PAC Manager).
Now, all that said, if you just want to send un-authenticated emails, you don't need to use either a DNS (because you are not resolving a domain name into an IP address), or a gateway IP address (because the email server is NOT on the internet, its inside your business network).
To send an email with no authentication, just make sure from your IT guys that the email server will accept an email with no username or password, run the chart that Nick linked to, and your done.
Just a heads up. Way back in the day, it was pretty common for email servers to no require a user or password, spammers took advantage of this and wrote their junk to just spew forth.
IT guys soon caught onto this and 'open relay' email servers were shut down big time. Most IT guys close them up tight because now days if your email server sends out a lot of emails, it can get blacklisted by the internet and its a really big hassle to get it unlisted.
Quick for example. Here at Opto 22, our email server is NOT open relay. Yet for the longest time our PAC Controllers could only send unauthenticated emails.. what to do? We had to email the IT guys the IP address of our PAC Controller and they would go into the settings of the email server and 'white list' just that IP address of the controller. This way, when an email came from that IP address, the email server would relay, or allow it to go out with no username or password. All other unauthenticated emails were rejected.
So, all that aside, to answer your exact question.
NO. There is no way to use the SendEmail command without authentication.
The only way our controllers can send an email with no username or password is to use the chart that a whole bunch of us have been using for years and year and years.... The one that Nick linked you to.
Lets know how you get on.