[nflug] FYI: Reverse DNS and sending mail to the list

[Darin Perusich]

hello all,

this is a little FYI in reguards to sending email to the nflug mailing 
list. if the reverse dns of the machine connecting to the nflug mail 
server does not resolve or resolves incorrectly then your message or 
messages will bounce. the error will be "450 Client host rejected: 
cannot find your hostname". you may get the bounced message and this 
text will be within the message or if you run the server the mailq 
command will show this.

we're running a combination of postfix, amavisd, spamassassin, clamav, 
and razor to filter all incoming and outgoing messages. messages being 
bounced with the "450 Client host rejected: cannot find your hostname" 
are being stopped by the postfix UCE Controls, see 
http://www.postfix.org/uce.html for all the details.

to see whether or not you can perform a reverse dns lookup on your 
machine or mail server try the command 'host ip.address' or head on out 
to http://www.dnsstuff.com. dnsstuff.com is a great resource, check it out.

if you send email from the following hosts/domains you need to contact 
your hostmaster and have them fix the reverse dns. we're bouncing alot 
from mail.voluntarygateway.ca and cnrcimc1.cnrc.navy.mil. the ipaddrs 
associated with the hostnames do not resolve. i'm not calling anyone 
out, i'm simple informing you of a misconfiguration.

if you have any questions in reguards to this feel free to contact me on 
or off list. if your messages are being bounced try me a "darin (at) 
darins.net"

-- 
Darin Perusich
Unix Systems Administrator
Cognigen Corp.
darinper at cognigencorp.com
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