When an email message fails to get delivered either to the inbox or the spam folder, we say it bounces. Sometimes the bounce is temporary (a “soft bounce”), and sometimes the failure is permanent (a “hard bounce”). Bounces are a fact of email life.
Sometimes they result from mistakes or problems that are beyond your control, and sometimes they happen because of something on your side with the message itself or your email set-up.
In order to run the most effective email campaigns possible, you must understand why emails are bouncing and what you can do to reduce them.
5 Reasons Your Email Bounces
1. The email address was entered incorrectly at opt-in.
People make mistakes when filling in online forms on your website from a computer or on a tablet or smartphone screen. Or, a clerk who typed the address into a point-of-sale system heard wrong or misread a handwritten address on a form.
2. The recipient’s mailbox is invalid.
An invalid mailbox either doesn’t exist or belongs to a closed account.
- Beyond typos, your subscriber might have deliberately entered incorrect information in order to enter a contest or download content without signing up for your email. Or, she closed her AOL account and switched to Gmail.
- You’re prone to this error if you buy or rent email address lists, because you don’t know how many of those addresses are still valid until you send to them.
- An abandoned email address can generate soft bounces. This happens when messages pile up until the mailbox reaches capacity. The mailbox is valid, but it can’t accept new messages.
3. A server blocked the message because it violates a rule.
Your message might be too large or improperly formatted, contain banned content or come from a prohibited domain. In some cases, the message is fine, but you sent it to a spam trap, an email address set up to catch unsolicited email.
4. A server blocked your sending IP address.
This is a permanent failure. It happens for many reasons, including these:
- Your IP address is blacklisted for suspected spamming or email fraud or has other reputation issues.
- Your email isn’t properly authenticated, or the sending address can’t be verified.
- You hit too many invalid mailboxes.
- You hit too many spam traps.
- You triggered too many spam complaints from recipients.
Some ISPs will block your IP temporarily if it’s too new to have reputation data.
5. The server is temporarily overloaded or unavailable.
This generates a soft bounce. The problem isn’t with your email system, your IP address, or your message but something on the recipient’s end. These servers usually save messages in a queue and deliver them after the problem gets fixed.