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Untrusted Java apps - and suspicious end users
The digital radio scam
HVR1110 working in Linux
English weather
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What's in a team?
How to run two instances of Tomcat on your machine
Database caching in Java
Britain needs a better anthem
New Age terrorists develop homeopathic bomb
Operators and Things
To Have or To Be
Speed limits
Apache vs nginx?
OpenWRT ad blocking
Running out of IPv4 address space?
Teach a man to fish - humorous alternatives
Support the BBC
Thoughts on digital copyright
Channel 5 - turn the volume up!
What really did happen on 9/11?
Postfix Antispam
How to update your Nokia N80 to the N80 Internet Edition firmware
Amazon's bad move
Root to bind ports under 1024?
Amateur radio
New York, 2010
Russian sayings
IPv6
HOWTO: Linux and iSCSI
Death of a hard drive
Monitoring PermGen usage
Cricket
F1
One time pads
Enjoyable development
Compiling gqrx on CentOS
Let's Encrypt
Offsite backup with iSCSI
Plus symbols in email addresses
TV series to watch
Qubes
Gaming in the cloud

Comments


Give a man a fire and he's warm for the day. But set fire to him and he's warm for the rest of his life. (Terry Pratchett)
Give a man a fish and he will eat for a day. Teach a man to be gay and he'll eat cocks for the rest of his life.
Give a man a fish, and he eats for a day. Give a man improperly prepared pufferfish, and he eats for the rest of his life.
Opera/9.80 (Series 60; Opera

Mini/7.1.32444/31.1395; U; en)

Presto/2.8.119 Version/11.10

Of course, there'll always be some mail servers that don't follow the RFCs properly.

Checking the logs, I noticed the following:

Sep 26 03:11:47 hosting postfix/smtpd[19263]: connect from mail7.exchange.microsoft.com[131.107.1.27]
Sep 26 03:11:49 hosting postfix/smtpd[19263]: NOQUEUE: reject: RCPT from mail7.exchange.microsoft.com[131.107.1.27]: 450 4.7.1 <df-gwy-07.exchange.corp.microsoft.com>: Helo command rejected: Host not found; from=<a.user@exchange.microsoft.com> to=<a.user@a.domain> proto=ESMTP helo=<df-gwy-07.exchange.corp.microsoft.com>
Sep 26 03:11:49 hosting postfix/smtpd[19263]: disconnect from mail7.exchange.microsoft.com[131.107.1.27]

Now, according to the SMTP RFC (http://www.ietf.org/rfc/rfc2821.txt):

The domain name given in the EHLO command MUST BE either a primary
host name (a domain name that resolves to an A RR) or, if the host
has no name, an address literal as described in section 4.1.1.1.

So why isn't there a DNS entry for df-gwy-07.exchange.corp.microsoft.com?

Anyway, to allow these broken setups to skip the "reject_unknown_hostname" in "smtpd_helo_restrictions", (as I don't want to disable it - it catches 95% of the spam) - you need to do the following:
* In main.cf, add parent_domain_matches_subdomains = yes
* In the smtpd_helo_restrictions section, add "check_helo_access hash:/etc/postfix/helo_access"
* In that helo_access file, list the offending "HELO/EHLOs" - in this case:

.exchange.corp.microsoft.com OK

* Finally, run postmap /etc/postfix/helo_access to build the DB file, and restart postfix.

It does appear to be a problem more with some mail server admins than others. (https://www.nearlyfreespeech.net/about/email.php#software)

Feed a man fish - and then he wants chips.
Give him chips and he asks for peas.
Why not cut out the fish, make him a vegetarian, and help restore the balance of cod in the North Sea ???

Give a man a fish, he'll eat for a day, give a man a fishing pole and he'll choke on it.
Give a man a fish he'll eat for an hour, give a man a wooden fish he'll be gnawing on it for a day.
Give a fish a man and it's probably JAWS!
Give a man eating fish in a restaurant pepper and it spices up the flavor, give a man eating fish some pepper in the sea and it spices up the you.
Give a man a dog and he can take it for a walk, give a man a fish he can take it for a drag.

give a man a poisoned fish and he will be fed for the rest of his life.
give a man a fish and you feed him for the day. Teach him how to fish you'll have to hear about the big one that got away fro the rest of your life
Give a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life!