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The Do's and Don’ts of Email Subject Lines to Avoid the Spam Folder

By Brett Casella

The Do's and Don’ts of Email Subject Lines to Avoid the Spam Folder

Email has been, and continues to be, one of the most viable outlets available to inbound marketers worldwide.

With the average business person receives more than 100 emails every day. Your messages are in a fierce competition with advertisements, newsletters, and memos toget read.

Your subject line could very well make or break your entire campaign, so it is nothing to brush off.

This isn't something you should take lightly. In that quick, rich snippet you need to grab their attention. Don't waste their time. It could result in your email being deleted and marked as spam.

I've highlighted the most important do's and don'ts to ensure that your email subject lines don't send your emails directly to the spam folder.

The 5 Do's of Email Subject Lines

Keep It Short & Sweet

Emails with subject lines of 50 characters or less have been proven to generate more opens and clicks than their lengthier counterparts. You don't need to write a Dickens novel. But seriously, the sweeter the better.

Personalize Your Message

What easier way to make your customer feel important than by simply including their name in your message?

Few things are worse than the generic “Dear Valued Customer” opener. These types of emails are the best way to show the customer that they aren't just another number in your database. In an article by HubSpot, Jeanne Hopkins stats "Personalization is about creating a natural process of conversation between companies and customers."

Tell the Benefit

This should go without saying, but nobody is going to open the email if they don’t think there is a benefit. Whether you are referencing a promotion, an ebook available for download, or a company press release, make sure the customer knows what they are opening.

A/B Test

Not sure if a certain subject line will increase open and click-through rates compared to the other? Develop an A/B test.

Constantly monitor your results and test your subject lines using the A/B method; create two emails with minor differences in wording, sending each email to 50% of your list, and track the results.

Be Consistent

Your customers were born, but it wasn’t yesterday; don’t try to pull a fast one on them with misleading subject lines. This will likely increase the number of people unsubscribing, as well as landing your email in the spam folder. No one wants to have a bad email marketing reputation.

Make sure what’s in the body of your email is what is promised in the subject line.

The 5 Don'ts of Email Subject Lines

Use Caps Lock


Anyone else get the feeling they were being yelled at?  Cause I sure did. Not very pleasant, is it?

Your customers don’t yell at you, so treat them with the same courtesy. The caps lock button may help you stand out, but it won't be in a good way.

Use Exclamation Points

Much for the same reason as above, exclamation points convey yelling. Besides that, they are generally corny and can come across as spammy.

Use Obscure Symbols

This is another sure-fire method to make sure your email winds up in the spam folder. Symbols such as @#$^%& can all trigger spam detectors and get trashed by a filter before your subscriber has a chance to trash it themselves. The only time you should be using @ and # is while you're engaging with prospects, leads and others on Twitter.

Don’t Be Salesy

Mailchimp said it best, “When it comes to email marketing, the best subject lines tell what’s inside, and the worst subject lines sell what’s inside.” This is a way to get lost with the 80 other subject line sales pitches. The point of the subject line is to get the reader to open the message, don't show your whole hand here.

Use Spam Filter Language

“Free”, “Act Now”, “For A Limited Time Only”, “Visit Our Website”, “Guarantee”. If these terms don’t set off the automated spam filter, they will set off the individual’s instinctual spam filter. These are all red flags and are pretty much synonymous with illegitimacy. 

Free Assessment:

How does your inbound marketing measure up?
Take this free, 5-minute assessment and learn what you can start doing today to boost traffic, leads, and sales.


Email Marketing
Published on June 19, 2013

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