One of the most common questions I get when helping marketers with their email marketing, is related to certain words being in the subject line of a marketing email. “Don’t use FREE in all caps, don’t use exclamation points, don’t use terms like ‘Offer expires’ or ‘last chance’ if you want your mail delivered!” are some oft-repeated bits of advice for helping get mail into the inbox.
This advice, in the past, may have been correct, but filtering has become much more sophisticated. Specific words don’t have nearly the effect they may once had, and the problem with that advice is that spammers can also just….not use those words, which renders the advice virtually useless. As spam has evolved, so have spam filters, and filtering based on trigger words just isn’t enough anymore. Spam filtering, as much as we want it to be, isn’t nearly as black and white as ‘use this word instead of this one’.
I ran a test on this to prove it, sending to a Gmail account, a Yahoo account, and an account managed by Office 365 with the following subject line:
FREE seminar to learn how to make more money!! $$ Cash for you, offer expires soon!!
That subject line breaks a bunch of commonly held “rules” in that it has:
- FREE in all caps
- Four exclamation points
- Dollar signs
- Offer expires soon
With a subject line like that, common knowledge dictates I’d never see this email in any of my accounts, it would go straight to spam. Realistically, it hit my inbox (promo folder for Gmail, as expected) on every email account I tested. This makes sense in the context of the technical implementation of subject lines, as receiving servers really only treat this as the same as email content. Subject lines aren’t treated as special pieces of an email for filtering purposes. In fact, a subject line isn’t even entirely necessary in order to send an email!
So there’s some proof that words in the subject line don’t change the way the email is filtered. Exclamation points also won’t trigger those filters and send your mail directly to the spam folder. The best way to avoid the spam filter is to make sure you are sending legitimate, wanted mail that is relevant to your users. Avoiding certain words won’t help you, but it also won’t hurt you, so go forth knowing you are FREE to use whatever subject line you want to use!