On Mar 1, 2018, at 05:07, Philipp Berger <newsletters at philippberger.de> wrote: > mail address like a"@"b at mydomain.tld, which by RFC should be valid Shouldn't it be "a at b"@mydoamin.tld ? -- My main job is trying to come up with new and innovative and effective ways to reject even more mail. I'm up to about 97% now.