Smart entrepreneurs know the lasting power of email marketing. With an ROI of up to $45 for every dollar spent, helps businesses increase both customer loyalty and sales. But simply sending emails is not enough. Companies that see a high email ROI have one thing in common: a carefully curated and maintained list.

Because while investing in growing your email list is smart, to be sure, adding more contacts to a database is just the beginning. You must also nurture, maintain and prune the community you have gathered.

To convince and convert, they need to get where your subscribers can see them. Getting into the habit of managing your list is the first step to avoiding it spam folder and reliable inbox landing. Maintaining your health also affects your sender reputation, which is an outcome that every email sender develops over time.

Some factors that affect your reputation:

• Many jumps: Inbox providers see this as an indicator of spam, as spammers tend to send to as many addresses as possible, even invalid ones. A bounce rate of 2% puts your emails at risk of going to spam.

• Spam complaints: Email providers take this type of user feedback seriously. If your content bothers people, it belongs in the junk folder. A complaint rate higher than 0.1% is dangerous.

• General engagement rates: Poor open and click-through rates indicate that an audience has little interest and can be reason enough for emails to start dropping out of the inbox.

Clearly then, managing your list the right way will help boost your reputation with email providers. Here's how to do it, and see consistent ROI from newsletters and campaigns.

Connected: How to grow an e-mail list that can earn you money

1. Remove dangerous data religiously

With returns counting so much toward the sender's reputation, you need to make sure that shipments go to valid addresses. On average, at least 23% of the email lists become invalid / ineffective with each passing year, so removing such contacts is a must. A capable verification service will eliminate invalid and dangerous addresses and also help you comply with basic delivery rules.

2. Eliminate invalid and/or false data

Verifying your email list quarterly allows you to cut down on data that has gone bad and helps avoid collecting more of the poor quality. To keep fake and invalid registrations at bay, make sure each subscriber confirms they are they want to receive from you (consider using double opt-in – requiring each person to click a subscription confirmation link). It's also a good idea to protect your registration forms with a real-time email verifier, which will reject misspelled and fake addresses and thus prevent them from messing up your database.

Connected: 4 ways to stop your emails from going to spam

3. Say goodbye to unengaged prospects

It's hard to part with subscribers you've worked so hard to acquire, but if they don't open your emails for more than six months, they MUST go Some companies are even more drastic about cutting off unengaged contacts and do it every three months. Whatever your approach, regularly analyze metrics and filter out dormant subscribers at least twice a year. Unopened emails affect your reputation and email marketing ROI.

4. Keep unwanted reports low

Paying attention to spam reports has always been important, but since Google and Yahoo got involved new shipping instructions, keeping a low complaint rate is an absolute must. Email providers know that even legitimate senders can get spam reports, but rethink your strategy if you get more than one complaint per 1,000 emails. Also, never email a subscriber who reported you again.

Connected: How to avoid spam complaints

5. Organize subscribers into segments

Are you sending the same message to an entire email list? This might work if you have a small business and only communicate general offers, but if your company is growing and you want to take your marketing to the next level, segment your list based on demographics and purchasing behaviors. 57% percent of traders prove that personalization helps them achieve better email engagement.

6. Monitor and analyze metrics

Measuring your results regularly is one way to increase the chances of success of any campaign. Which emails work best? Your subscribers' feedback will tell you. Except open rates, keep a close eye on click metrics to learn what your bids and calls to action include. Also, if any of your emails get a high unsubscribe rate, try to find the cause so you can better retain an audience. And, although often overlooked, response rates also play a positive role in email delivery.

In all approaches, try to understand what kind of content drives people to write to you, and double that positivity!

Connected: 5 Simple Fixes for Better Email Delivery