Can we put the FREE!!! Myth to bed?

Really. Single words in the subject line don’t hurt your delivery, despite many, many, many blog posts out there saying they do. Filters just don’t work that way. They maybe, sorta, kinda used to, but we’ve gotten way past that now.
In fact, I can prove it. Recently I received an email from Blizzard. The subject line:
Laura — Last Chance to Claim Your FREE Copy of Warlords of Draenor — Including Level 90 Boost! Offer Expires Monday! Last Chance to Claim Your FREE Copy of Warlords of Draenor — Including Level 90 Boost! Offer Ends Monday!
We have an email with

… two instances of FREE in all caps

… 4 different exclamation points

… Offer Expires

… Last Chance

… Unsubscribe

all right there in the subject line.
And what does Spamassassin say about the mail?

X-Spam-Flag: NO
X-Spam-Status: No, score=-7.193 tagged_above=-999
required=6.31 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1,
DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1,
HTML_IMAGE_RATIO_04=0.556, HTML_MESSAGE=0.001,
RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=-0.01,
RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_RP_SAFE=-2,
RP_MATCHES_RCVD=-1.428, SPF_HELO_PASS=-0.001,
SPF_PASS=-0.001] autolearn=ham
autolearn_force=no

See that first line? X-Spam-Flag: NO
See the next line: score=-7.193. Notice the negative? That’s almost 14 points less than what is needed for our installation of SpamAssassin to mark a message as spam.
Words in the subject line are not used for filtering in any sane filter.
Exclamation marks don’t trigger filters. 
FREE does not trigger filters. 
It’s time to retire the myth that spam filters pay any special attention to the subject line. They don’t. In fact, to a mail server the Subject line is just another bit of content. One that is only special because it starts with a defined field name (Subject), has a colon and contains a line terminated by CRLF. In fact, a subject line isn’t required for an email.

The only required header fields are the origination date field and the originator address field(s). All other header fields are syntactically optional. More information is contained in the table following this definition. Section 3.6, RFC5322

Section 3.6, RFC5322

Filters don’t treat the subject line any differently than the rest of the email content.
(For the Horde.)

Related Posts

Truths and Myths about email deliverability

virtualShow_forblogKen Magill will be interviewing me on the Truths and Myths of Email Deliverability, November 12 at the 2015 All About eMail Virtual Conference & Expo. Ken has a bunch of questions he wants to ask me, but he’s also expecting to take a lot of questions from the audience as well.
Speaking of myths, there has been discussion lately about recycled spamtraps. Apparently, there are people who believe (believed?) that every ISP uses recycled spamtraps. When Hotmail and Gmail said recently they didn’t use recycled traps people got very upset that they believed something that was not true.
It’s a mess. There is so much about email that is like a version of telephone. One person says “hotmail uses recycled spamtraps” someone else repeats “big ISPs use recycled spamtraps” then then third person says “all ISPs use recycled spamtraps.” People try and correct this type of misinformation all the time but sometimes it’s hard to clarify.
So show up to our session and let Ken lob questions at me, lob some of your own and we can see what myths we can clear up.

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Content based filtering

Content filtering is often hard to explain to people, and I’m not sure I’ve yet come up with a good way to explain it.
A lot of people think content reputation is about specific words in the message. The traditional content explanation is that words like “Free” or too many exclamation points in the subject line are bad and will be filtered. But it’s not the words that are the issue it’s that the words are often found in spam. These days filters are a lot smarter than to just look at individual words, they look at the overall context of the message.
ISP_tolerances
Even when we’re talking content filters, the content is just a way to identify mail that might cause problems. Those problems are evaluated the same way IP reputation is measured: complaints, engagement, bad addresses. But there’s a lot more to content filtering than just the engagement piece. What else is part of content evaluation?

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Images in the subject line

I’ve seen this trick used by a few senders recently, with varying effectiveness.

Where do they get these pictures?
While you can scatter any images you like across the body of your message, the subject line is limited to just text. But “text” is more than just “a, b, c” – using RFC 2047 encoding you can use any character you like, including many tiny pictures.
⛄ 💰 🐘 ✈ 🎁 ☂
☀|||||||☀
Experian, Vertical Response and Bronto all have some interesting things to say about the effectiveness of using these.
Finding the right glyph can be tricky. Macs have a fairly decent glyph search engine (under Edit > Special Characters… in most applications) while Windows has a fairly mediocre one (Start > All Programs > Accessories > System Tools > Character Map > Advanced View). Both are missing some useful features, though, so I put together something better.
emailstuff.org/glyph lets you search for glyphs by name. It’ll tell you about related glyphs (“helicopter” and “airplane”, or “package” and “wrapped present”) which can help you find the right image when you don’t know it’s name. And, once you’ve chosen a glyph, it shows how to use it in various encodings (if you’re using a GUI tool or a web form to compose your emails you can probably just copy and paste, but it’s handy for manually editing messages when your composition tool isn’t unicode-friendly).
Will all your recipients be able to see these glyphs? All mail clients support utf-8 text and this sort of encoding so the only issue is whether the recipient has a font installed with the glyph in it. That’s operating system specific, rather than depending on the web browser or mail client, so if you want to test – and you probably should – you can get away with just Windows and OS X for desktop, iOS and Android for mobile.
Have fun! But don’t overdo it.

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