Sendmail: domain literal format
I have a German customer who wants all his domain names, mail servers passed in dnsreport tests.Diff. C class NS, multiple MX records are all done.
There is still one warning, the domain literal format. I believe it wouldn't me too much security risk to enable user@his_ip for his website. Although he's most likely not going to use it, but how can I enable it in sendmail.
# a class with just a left bracket (for identifying domain literals)
C[[
Not sure how I can tweak this. Any ideas.