I can’t set up an email alert.
I enter all the information and when I click on test sending, the error appears:[EFAULT] Failed to send email: [Errno -2] Name or service not known
Can be possible that Is related to the domain .com.br somehow?
What the complete error say?
I don’t think it’s because of the .com.br domain. I’m from Brazil and here our domain is like that.
Today there was another error.
off course, just pointing to that because sometimes email validators fails.
With the error above (pointing to a DNS failure), and well watching your previous screen i realized that you probably put in your smtp server as smtpS.uhserver.com instead of smtp.uhserver.com
Here in my email in outlook I use smtps.uhserver.com and it works.
In the TrueNAS panel I changed it to smtp and it still gives the same error
weird… did you try instead with the port 587?
Yes.
Same error too. 
I don’t see anything much wrong with the setup. I would try a couple things.
Make sure the username and password is correct.
Try taking off the S on STMP.
Maybe Truenas is internally adding an S for you and the sent result is SMTPSS
My mail service I believe uses SMTPS but I don’t need to add the S at the end to use it, Just make the right settings selections and use the 465 port.
SMTPS (Simple Mail Transfer Protocol Secure) is a method for securing the SMTP using transport layer security. Some email service providers allow their customers to use the SMTPS protocol to access a TLS-encrypted version of the “submission” service on port 465.
Post a picture of your Network-page and maybe we’ll see something there that can explain the failing DNS.