Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've configured SPF, reverse DNS and as far as I can tell I'm not on on RBL. I've attached a sample data below. I do not send unsolicited emails

X-Message-Delivery: Vj0xLjE7dXM9MDtsPTA7YT0wO0Q9MjtTQ0w9NA==

X-Message-Status: n

X-SID-PRA: root <>


X-Message-Info: 6sSXyD95QpWF3v7LS43fskI65ebhC9rrkAyBVONMSBEOsBjL5GCMK0iN2SvmTEaRM7RDhjy5mH1zlW270VXN6U3ANgKoEhqrFgXOoatdblE=

Received: from ([]) by with Microsoft SMTPSVC(6.0.3790.4675);

  Fri, 28 Jan 2011 17:50:15 -0800

Received: from (localhost.localdomain [])

 by (Postfix) with ESMTP id 2BECD150A0FAA

 for <>; Fri, 28 Jan 2011 19:50:15 -0600 (CST)

Received: by (Postfix, from userid 0)

 id 167DE150A0FAB; Fri, 28 Jan 2011 19:50:15 -0600 (CST)


Subject: welcome

Message-Id: <>

Date: Fri, 28 Jan 2011 19:50:15 -0600 (CST)

From: (root)


X-OriginalArrivalTime: 29 Jan 2011 01:50:15.0675 (UTC) FILETIME=[E005A4B0:01CBBF56]

to the daily challenge
share|improve this question
Can you get the logs from your mail server? – Jacob Jan 29 '11 at 2:07
Could you show some headers from messages that have been marked as spam? – Antonius Bloch Jan 29 '11 at 4:35
Can you also show us the content of one of the emails? – Mike Scott Jan 29 '11 at 6:36

It's really tough to say why Hotmail is blocking you. It may have nothing to do with your SPF. You could try changing your SPF to this:

v=spf1 ip4: a -all

I switched it from ~all (which is softfail meaning "all others should be allowed but don't necessarily trust it") to -all (which is hard fail meaning "all others should be rejected"). They might trust your actual whitelist more.

A few other things to try:

  • Give your mail server an actual hostname (e.g., but be sure to update your SPF if you do this)
  • Pass the content of your messages through Spamassassin for testing, try to get a score of 0
  • Set up domain keys (hey, anything helps, right?)
  • If you're batching messages (i.e. sending mail to multiple recipients with a single connection) try sending doing every message with an individual message
  • If you're opening a new connection for every message, try batching them
  • Relay the messages through Google's SMTP server (since that's your MX)

Unfortunately due to the nastiness of real spammers it's really hard to make sure certain mail won't be flagged as spam. If it were easy there'd be a lot more spam. The big guys (Google, Yahoo, Hotmail) have their own system for spam tagging and they're very secretive about it. If word got out how/why their algorithm works the spammers would take advantage of that in a heartbeat.

Good luck.

PS I love Words With Friends. Thanks for making it.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.