Building an email list and communicating with prospects and customers is one of the smartest marketing moves a small business can make. However, emails often “bounce,” which means they don’t land in the intended recipient’s inbox. Why? Below are six common reasons why your emails are bouncing along with tips on how to fix these problems.

The email address doesn’t exist

Some people make up fake email addresses when filling out forms or surveys because they don’t want to give their real email addresses and get inundated with spam. Others may have intended to enter their correct email address, but made a typing mistake. Meanwhile, people leave their Internet service providers and employers, which eventually renders their associated email addresses invalid.

To combat fake email addresses, make sure you’re clear about your own emailing intentions. Will you send a monthly newsletter? Is it easy to unsubscribe?

Some typos, like @gamil.com instead of @gmail.com are easy to identify and rectify. If you have a bouncing subscriber’s additional contact information, reach out to confirm the email address.

The email is undeliverable

Perhaps you made a typo when entering the address? Other reasons for undeliverable email include an offline server. Servers do go down for maintenance and other reasons, but they usually come back online soon thereafter. Try again in a few hours.

Your email has been blocked

This doesn’t necessarily mean that the subscriber no longer wants to receive your email messages. Some workplaces have strict filters that limit the type of messages they’ll allow onto their systems. Likewise, some Internet service providers restrict certain services if those services have been known to send spam.

To solve this type of problem, you may need to contact system administrators at the organization that’s blocking your messages and ask that they unblock them.

The recipient’s mailbox is full

Once someone’s mailbox is full, that’s it until the person removes some of the mail clogging it up. This can be a temporary problem because once the individual deletes mail, new mail can be delivered. However, this can also be a sign of an abandoned email address. Try again in a few days, or contact the individual to let them know their email inbox is full.

Your message is too big

Some receiving servers have file size limits, rejecting messages that are above and beyond those limits. If your email message contains high resolution graphics, it can easily exceed limits and be rejected by the server. Thus, the email bounces.

To solve this problem, resize your graphic files or use lower resolution versions.

Finally, periodically clean your list, removing subscribers that bounce frequently (if your software doesn’t automatically clean the list). Sending too many messages that bounce tells external ISP and systems administrators that you might be a spammer, even if you aren’t. They’ll automatically block you, which will further impede the deliverability of your messages in the future.