North American Network Operators Group|
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Re: Underscores in host names
There are also mail domains to consider. They have superficially the same syntax as host names (they cannot have a trailing dot) but they are generally checked much more strictly for conformance to that syntax. I'm not sure whether the original post was about a mail domain or the name of a mail host, but if it was the former I would be surprised if the customer could claim that it works most of the time. Names of mail hosts are another matter, especially the names they declare in HELO. When I analysed this back in December, I found that about 1/3 of legitimate mail hosts declared invalid hostnames. This is orthogonal to the issue of host name syntax, but it does show that being excessively strict will cause you pain. However it is worth checking mail host names for gross syntax violations since some fairly common spamware puts all sorts of binary junk in its HELO command. Tony. -- f.a.n.finch <firstname.lastname@example.org> http://dotat.at/ BISCAY: WEST 5 OR 6 BECOMING VARIABLE 3 OR 4. SHOWERS AT FIRST. MODERATE OR GOOD.