Whether you work in the nonprofit sector, real estate, e-commerce, public relations or any other field, you probably send out newsletters or offers to a large email list. And with good reason. According to a recently released survey by Adobe, the average worker spends more than five hours a day checking their email; no wonder email marketing campaigns are key to so many operating models.

However, if you’ve noticed that your open rate is low and your unsubscribe rate is high, there may be four good reasons why.

1. You’re sending too many emails.

The Adobe survey found most people check their email and social media account before they leave for work. In fact, more than 80 percent of people have checked their email by the time they arrive at the office. That gives you plenty of time to get customers to open emails and increase your click rates. However, 38 percent of respondents said companies solicited them too frequently via their professional email addresses, and that number increased to 43 percent for their personal emails.

If you’re inundating folks, they may feel overwhelmed and start glossing over them. The Adobe survey didn’t specify what constitutes “too many emails,” but if you’re trying to increase click rates and hit your email-marketing benchmarks by sending a high volume of messages, it’s probably backfiring.

2. Your emails are poorly written or too long.

Respondents to the Adobe survey said just 25 percent of emails from brands were interesting enough to open. This may be due to run-of-the-mill subject lines, poorly written copy, overly complicated language or even uninspiring visuals. According to the survey, office workers scroll through emails five hours a day. The vast majority of respondents said that achieving inbox zero makes them feel amazing and relieved, yet 10 percent also lamented that it “felt impossible.”

The message is clear. People would rather read interesting emails, and they delete boring ones. Some of the more advanced email platforms like Gmail actually notice peoples’s habits and eventually place senders that typically get deleted into a spam filter.

3. You aren’t personalizing your emails.

So what helps get your emails noticed? Personalization. This is especially true for millennials, 46 percent of whom in the Adobe survey said personalization is important to them. It’s wise to send an email newsletter with daily deals, but there are many ways to get this wrong. Fairly recently, I’ve deleted emails from companies that misspelled my name or recommended products that weren’t relevant to my needs.

Are you running a sale on men’s clothing in your East Coast stores? Make sure you’re not sending that email offer to a woman on the West Coast. You may cause some eye rolling and decrease the chances she’ll opt in for more emails. Nearly 20 percent of people said they felt most frustrated by expired offers. Keep that data in mind when personalizing emails. Send offers with enough time for someone to open the email and get to your store or website. This way they can actually use the offer rather than delete it because it’s no longer valid.

4. They’ve already bought what you’re advertising.

Perhaps you want to send emails about the latest sale you’re running on phone cases, chargers and headphones. Try to make sure whoever you’re sending it to hasn’t bought those products already. The Adobe survey showed that 15 percent of respondents listed this as their top annoyance. That means you can bet others find it annoying, too, even if it’s less irksome than other factors. When you send someone an offer for something they’ve already bought, it makes your emails irrelevant and shows you’re not paying attention to their needs.

Keep these factors in mind when developing or working to improve your email marketing campaigns. Use tools like Constant Contact, MailChimp or GetResponse to help manage them. If your bounce rates are high, or your conversion rates and average open rates are low, try writing snappier copy and subject lines. Many tools let you do a/b tests to help you figure out what gets better click-through rates. Optimize your emails for mobile devices. Lower your number of emails. When you do email, personalize those messages. Your company and your bottom line may be better for it.