How Do I Know if My Marketing Emails are Going to Spam?

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Jess Swazey
Jess Swazey



After weeks of carefully crafting content, thoughtfully segmenting a list of engaged and relevant contacts, and debating over the perfect subject line, you hold your breath and hit send on your latest big campaign.  But how do you know if your hard work was rewarded with a delivery to the primary inbox, or if your message went to the dreaded spam folder?


The truth is there’s no reliable way to know with certainty what happens to an email message once it has been delivered.

When a message is sent between a sender and recipient, an SMTP connection is opened between the two parties.  The recipient’s mailbox provider will either send back a yes/accepted response letting the sender know the mail was accepted, or a no/rejected response letting the sender know the mail was bounced back.  Once this thumbs up/thumbs down exchange occurs, the connection between the two parties is cut. Inbox providers don’t report back to senders on how a mail is handled or filtered once it has been accepted.  This keeps their mail filtering policies private, so they can’t be intentionally bypassed by bad actors or by well meaning marketers. No Email Service Provider (HubSpot included) is able to accurately report on inbox placement, since this data is not provided back from any recipient. 

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But aren’t there services out there that can report on inbox placement?

There are vendors that offer products that report on inbox placement.  Most deliverability focused vendors will use one of two methods to provide their customers with reports based on inbox placement: panel data or seed lists.

Panel data uses a panel of recipients across the globe that agree to allow their inboxes to report on where mails are placed.  Many of these recipients may use a free software that allows them greater control over their mailboxes in exchange for sharing their mail placement data.  Seed lists are a list of curated email addresses across mailbox providers that are in use solely to report inbox placement back to the vendor offering the list.  While both of these services can offer an email marketer some insight on how their messages are being placed, neither service is going to accurately reflect the inbox placement of the contacts within your recipient list.  As the contacts within a panel or seed list aren’t a 1:1 match for the recipients in your list, the data these services provides can’t accurately reflect the inbox placement for your database.

So how can I gauge inbox placement?

The best place to monitor the success of an email send is by measuring the engagement of your campaigns.  This data can be accessed from the post-send screen in the HubSpot email marketing tool.   Open rate is the best true metric you can use to understand if your emails are making it to the primary inbox of your recipients.  Open rates above 25% indicate that your brand’s sender reputation is healthy, and mail is hitting the primary inbox. Open rates between 15-25% indicate that your mail may not be arriving in the spam folder, but could benefit from further optimization.  Open rates below 15% indicate that your mail could be getting filtered to the spam folder. If your campaigns consistently see open rates of 10% or less, this is a strong indication that your sends are being affected by graymail and much of your messaging is likely being delivered to the spam folders of your recipients.  

To improve a declining open rate, be sure to focus your sends on only contacts who have provided direct permission to your brand to be included in your marketing efforts, and those that have recently engaged with your email.  You can promote a healthy sender reputation by using HubSpot’s graymail suppression feature and creating a sunset policy to regularly remove or suppress unengaged recipients from your marketing sends.

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