Gmail spam filter Vs. Spamassassin

The official Google website says:

Google continues to work on spam filters to keep unwanted messages out of your inbox. However, spammers are deviously clever and adaptive. Defeating them will require your help. If you see a spam message, use the Report Spam feature to squash it. The spam will automatically be removed from your inbox and information about it will be reported to our quality team.

This means that the Gmail Spam filter is constantly learning the new spam behaviors, it stores each user click on the check this as spam button. But what if my mail gets caught by mistake by the Gmail spam filter? This issue is known as the “false positive” spam filter mistake. Gmail for the moment is not offering a I’m not a spammer button. Reading non-official sources today I discovered that SpamAssassin seems to be included inside Gmail’s master spam filter. How incredible, I know perfectly each spam rule inside SpamAssassin since I check my emails before each send with my colleague Luca’s homemade software* that incorporates Spamassassin rules set; and Gmail spam filter rates are not clear as spamassassin rates. Gmail spam filter has two options: it displays your emails in inbox… or spams them (they go straight to junk folder).

All the complex Gmail spam rules rate generation is invisible to our eyes

Well, most of the spam rules are based on common spammers’ behavior… but the spammers behavior is based on eluding each spam rule! So how can I get out of this recursive maze? Some clever guy uses Gmail as a spam filter check. It’s possible to send to our gmail account the email that we want to check, and then forward to our email client each email with gmail’s pop forwarding feature. So if the email gets back to our sending client, this means that Gmail is not seeing that email as spam.

But wait: Gmail spam filter is not identical for each client, since it must contain a different white list for each user (the email address of your friends for example… you can try sending a dangerous topic email to your friends, your email will be forwarded, since you are in their Gmail’s trusted network) .

So, who’s the winner? SpamAssassin or Gmail?

This Gmail homemade spam check is powerful but dangerous because of the differences between each gmail user settings; while SpamAssassin rules set is clear and has a fast integration on your machine without wasting time (*yes, check our download section if you want to try our free spam rate validator software).

What can I do to avoid gmail spam filter?

The best practice is having your email marked with a “not spam” action button in your custormer’s inbox.

Faking X-mailer email field never rewards

X Mailer

Some email clients can fake the sent email’s X-mailer text. This is a very dangerous option to choose if you want your emails to stay away from spam folder.

When the email is composed, the X-mailer text is not the only common field filled by the origial sending software: there is also the X-MimeOLE field.

Microsoft Outlook Express attaches this MimeOLE: V6.00.2900.3138. This number depends obviously by the version of Outlook Express we are using, but not many bulk emailers can fake the MimeOle field too. Composing an email message pretending to be read as a common Outlook Express’ email and mistaking the final composition can result in a catastrophic spam score (if we were playing monopoly this means go straight to jail!).

If we are sending our email with a powerful bulk emailer that enables to change the X-Mailer text, and we pretend to be sending from Outlook Express in order to optimize our inbox rate, we are doing a great mistake: being caught by the Forged_Mua_Outlook SpamAssassin common spam rule after our email sending operation causes our email to get 3.4 spam points (very high spam rate, and very bad)…

Plus, if we are not careful in email composition, we can get additional 2.4 points for the Forged_Outlook_tags broken SpamAssassin common Rule, since Outlook has a very particular way of building html for the emails, it’s pretty easy to see if an email has been composed by another email client’s html composer.

Faking X-mailer field is not a useful way to raise email inbox rate, even though it seems appealing. Keeping your email client or bulk e-mail sender identity clean (or at least leaving empty the x-mailer field) is the best option for your clear conscience and for your inbox rate.

Tests: you can do your own tests with our SpamAssassin engine spam checker software: try to modificate the x-mailer (you can try with SendBlaster Free Bulk Emailer) text and spam check your mail, then leave the original x-mailer text, and spam check your mail again. Then take a clean Outlook Express email and spam check it, you will notice heavy spam points decreasing.

Email content spam check rating

As we learned in the past months the spam filters tests work in different application layers. In a single email sent from a sender to a recipient, we can analyze many possible spam engine alerting contexts:

  • Sender Network
  • Sender Address
  • Email source (html)
  • Email source (txt)
  • Content
  • Links
  • Words
  • Images
  • Percentage Text on Images

A spam filter network can focus on a single context, for example SURBL lists each url contained in the email source. Many spam filtering networks are distributed and collaborative: Vipul’s Razor constantly updates a huge list of statistical signatures that can spot spam messages even though they are mutating in form and behaviour. This means that if your are spotted as a spam sender, of if your emails are signed as spam, every client in the Razor is seein your email as spam, until some one marks you as a clean sender again. Getting back from spammer status can be very hard.
For this reasons we should try to send emails as spam free as possible, and only to our mailing list subscriber. Now I analyze with Mailing Check (that incorporates SpamAssassin engine rules set, and incorporates Razor and SURBLS blocklists) the latest spam message that I received this morning:

This are the spam points scored by each single entry
Spam Score – Reason

  • 3,6 – Contains a URL listed in the SC SURBL blocklist
  • 3,4 – Contains a URL listed in the JP SURBL blocklist
  • 3,3 – Contains a URL listed in the AB SURBL blocklist
  • 2,6 – Contains a URL listed in the OB SURBL blocklist
  • 2,5 – Listed in Razor2
  • 1,5 – Razor2 gives engine 8 confidence level above 50%
  • 1,5 – Razor2 gives engine 4 confidence level
  • 1,5 – Contains a URL listed in the WS SURBL blocklist
  • 0,5 – Razor2 gives confidence level above 50%

In this example we see how can be dangerous being listed in SURBL blocklists.
This email gets 20,4 spam points that means a very bad spam rating (it was in my spam folder). Now if we analyze each spam point source we notice that the spam points assigned for high confidence level are few, compared with points assigned for URLS contained into SURBL blocklist. The Razor confidence level means how likely the message is spam. This spam point source is assignerd depending on each email mime part and checked, then Razor gives a score.

New standalone email spam checker

Spam check setup window

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We got a brand new installation setup for MailingCheck software.

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  • Email content spam checker
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  • SpamAssassin engine included
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  • Can check emails for spam rates before sending
  • Grows bulk email inbox rate
  • Best offline email spam detection tool

Now you can install our little email spam scoring software without the need of SendBlaster (anyway, you can try the bulk emailer free version). Find and clean your email spam source, oh yeah!

Free spam check test

Download here the freeware software for spam check and spam score test (11 Mbytes).

MailingCheck Spam test software features:

  • analyze your emails spam level before sending
  • free software download
  • Email content spam test checker
  • Email spam rate points results
  • Customizable spam point ranges
  • SpamAssassin test engine included
  • Email spam cleaning suggestions included
  • Razor Engine included
  • SURBL blacklists included
  • Optimizes your bulk email software and boosts your bulk inbox email sender rate
  • Best offline email spam detection tool

Definition of SPAM

I found this interesting definition of SPAM in the spamhaus project

The word “Spam” as applied to Email means Unsolicited Bulk Email (”UBE”).

Unsolicited means that the Recipient has not granted verifiable permission for the message to be sent. Bulk means that the message is sent as part of a larger collection of messages, all having substantively identical content.
An email message is Spam only if it is both Unsolicited and Bulk.

  1. Unsolicited Email is normal email (examples: first contact enquiries, job enquiries, sales enquiries)
  2. Bulk Email is normal email (examples: subscriber newsletters, customer communications, discussion lists)

Technical Definition of Spam: An electronic message is “spam” IF

  1. the recipient’s personal identity and context are irrelevant because the message is equally applicable to many other potential recipients;
  2. AND
  3. the recipient has not verifiably granted deliberate, explicit, and still-revocable permission for it to be sent.

So after reading this definition I thought “is that something missing? Or it’s just a matter of permission and identity?”. In my country (Italy) a lot of bad translated email messages are delivered everyday. No-one reads anymore these emails, but they are still sent and written (and badly translated), what’s the market behind that spam email sending, that makes it sustainable? All those spam messages in a bottle are flooding our virtual beaches.

There are many retailers for drugs, pills, strange furniture, music CDs, software… all those people are sending new mass emails everyday without caring for the global time wasting action they are doing.

As polite email marketers we need to difference ourselves from these common spam emails, we have to give to our readers something different, our mass emails must be different. And what’s the only thing that a computer text cannot fake? It’s human personality.

In this scenario, the only behavior for our polite, opted-in bulk emails it to send mass emails only to subscribed users in our mailing list. What if we get caught by the spam-filters network before we get to our prospect’s inbox?

Here’s my personal list for what I understood about email marketing

  1. We can check our email for spam rate before sending
  2. We can build an opted-in user-base
  3. We can closed-loops double opt-ins (closed loops on spamhaus)
  4. We can write spam-free emails
  5. We can ask our recipients if they got our email
  6. We can ask our recipients to put us in their white list
  7. We can write a meaningful subject our emails
  8. We can automate email subject merging
  9. We can write meaningful contents
  10. We can write cool call to action texts
  11. We can check your sender’s reputation