So since a couple of days I am using Gmail for my boerland.com domain. I like it. How much? Well, think gmail... Thats it. Plus you can create 25 accounts within your domain for free (no catchall (yet?)) and you can have distributed rights on who can maintain the users. Nicely done. With extreem cool anti spam feautres like gmail has.
Speaking of, since I was changing my DNS entry, I though I might as well add more anti spam features zo my zone using spf. I used this msft tool thingy to make up the TXT field. And then change it a lot because it is a stupid tool (you can make longer entries than the TXT field can hold :-( )
So I created this entry
boerland.com text = "v=spf1 a mx mx:google.com a:willydobbe.xs4all.nl a:aspmx.googlemail.com mx:upsilon.pair.com ~all"
And yes, that does
validate.
But before I know the syntax of the Gmail hosts, I needed to lookup the configs from the Google site.
Google says one should add "include:aspmx.googlemail.com". So I checked aspmx.googlemail.com and got:
aspmx.googlemail.com text = "v=spf1 redirect=_spf.google.com"
I re-read that line. And re-read it. That cant be true! Only loooooosers sysadmins of old NT boxes make such a stupid mistake!
But yes, that does include Google it seems.
_spf.google.com text = "v=spf1 ip4:216.239.56.0/23 ip4:64.233.160.0/19 ip4:66.249.80.0/20 ip4:72.14.192.0/18 ?all"
That might look like a smart way of using A record, redirecting and TXT field, but do checkout the underscore in the hostname! An underscore in a hostname!
Google are you barking mad?
Only letters, digits, and dash characters are legal in hostnames. Special characters other than the dash (and the dot between components) are not allowed in the hostname designation although cohesion may cause them to appear. Underscore characters are commonly used by Windows systems but according to RFC-952 they are not allowed. The use of the underscore has caused many subtle problems in systems that connect to the wider world...
(wikipedia, see also rfc 952)