Spam costs more than $4.99 for a 12-ounce can of the meat surprise at the supermarket. Nonprofits are losing an average of nearly $15,000 per year due to emails ending up in prospects’ electronic spam folders, according to a new study released by digital firm EveryAction.

The 2015 Nonprofit Email Deliverability Study analyzed 55 nonprofits with email lists of at least 100,000 names. About one in eight emails sent are not delivered to an inbox, according to the study. “The percent of email never making it to inboxes is almost as high as the percent of emails opened,” wrote Brett Schenker, the study’s author. “That is a frightening state of affairs for email delivery.”

If an Internet Service Provider (ISP) notices your emails are often marked as spam, are deleted immediately or are never opened, it might route your emails to spam folders or bar you from emailing. That, said Schenker, can take months or years to rectify.

Schenker lays out three reasons your emails might be ending up in spam folders.

• Not including a single-click unsubscribe: “If you make your unsubscribe process difficult, you’re running the risk of a user simply marking your message as spam instead, which is far more harmful to your email deliverability than unsubscribing,” wrote Schenker.
• Using an out-of-date email list: Schenker said if your email has never been opened or you haven’t received a response in six months, the address is probably outdated.
• Sending irrelevant email: Not all of your customers are interested in all of your content. You need to segment your list.

The study found that an average of 12.29 percent of emails were delivered to spam folders per month, with June having the highest rate at 14.82 percent and November having the lowest, 8.03 percent. Schenker determined that for every 1 percent of emails going to spam, a nonprofit loses $1,203.84 in revenue per year. At an average of 12.29 percent per month, that’s $14,796 per year.

Schenck had some tips for nonprofits looking to increase their email deliverability rate.

• Opt-in and confirm: Prospects should voluntarily sign up for your emails. Once they do, you should immediately send an email confirming that their address is correct. “By opting-in addresses and confirming them, you ensure the person on the other end absolutely wants to hear from you,” wrote Schenker.
• Ramp up your messaging with a welcome series: This will give you an idea of what to expect from your subscribers. People who read all the messages will be far more engaged than people who read none.
• Focus beyond opens and clicks: Conversion is the far more important metric. Test subject lines, test content, and drill down into segments.
• Focus on who isn’t getting the message: After two or three bounces, Schenker advises that you remove the address.
• Focus on inactives: Those who stop engaging or never engaged in the first place should receive messages designed to entice them to engage. If they haven’t after a year, they should be removed.

Work with your provider: “A good provider should work with you to monitor key deliverability metrics…, as well as acting quickly to fix problems like blocks and blacklisting before they get out of hand,” wrote Schenker.