Email Bounce Back

A bounce back happens when an email you send fails to reach the recipient's inbox. This article explains why bounces happen, how Titan's bounce limits work, and what you can do to reduce them and avoid your sending being restricted.

In this article

• What is a bounce back?
• Why do emails bounce back?
• Why Titan monitors bounce backs
• How to reduce bounce backs
• Bounce back limits on Titan
• Bounce back limits for email forwarders
• Troubleshooting

What is a bounce back?

A bounce back is what happens when an email you send can't be delivered. Your email provider sends you a bounce message explaining why the delivery failed, along with some technical detail about the failure.
 

Why do emails bounce back?

Emails most often bounce back because the address you sent to doesn't exist, is no longer active, or was typed incorrectly.

• The recipient's email address doesn't exist or is no longer active.

• There's a typo in the address — for example, gmial.com instead of gmail.com.

• The recipient's mailbox is full or their mail server is temporarily unavailable.
   

Why Titan monitors bounce backs

Titan tracks bounce rates for two reasons: to protect your account from misuse, and to protect your domain's reputation with other email providers.

It can be a sign your account is compromised

A sudden spike in bounce-back messages can mean someone has gained unauthorised access to your account and is sending spam from it. Titan flags this activity so you can secure your account before it causes further damage.

It protects your sender reputation

Mailbox providers like Gmail and Outlook track how often your emails bounce. A high bounce rate signals spammy or low-quality sending, which can get your domain blacklisted — meaning your emails stop reaching anyone at all, not just the addresses that bounced.

This is also why buying or using public email lists is risky: those addresses are often outdated or invalid, and sending to them drives up your bounce rate and damages your reputation with mailbox providers.
 

How to reduce bounce backs

A few habits make the biggest difference to your bounce rate:

1. Keep your recipient list current. Remove addresses that consistently bounce.

2. Never buy or import a public email list — you can't verify those addresses are valid or that people opted in.

3. Double-check spelling before sending, especially common typos like gmial.com instead of gmail.com.

4. Build your list organically, from people who've actively signed up to hear from you.

Bounce back limits on Titan

Titan applies bounce limits at both the domain and mailbox level. If you go over a limit, sending is paused until the limit resets.

Rate Limits for Domain

Email transfer with different domains

Email transfer within same domain

Rate Limits for Mailbox

Email transfer with different domains

Email transfer within same domain

If you reach your hourly limit, you won't be able to send more email until the next hour. If you reach your daily limit, sending resumes after 24 hours.

Bounce back limits for email forwarders

Email forwarders have a daily bounce limit of 20 per mailbox.

• If a bounce happens because the recipient address doesn't exist, Titan automatically removes that forwarder and notifies you.
• Once you hit 100% of the daily limit, forwarding pauses for 24 hours. During that time, incoming emails go to your inbox instead — even if the forwarder is normally set to not keep a copy.

Troubleshooting

Emails you send keep bouncing back

Problem: You send an email and get a bounce-back notification instead of it reaching the recipient.

Cause: The recipient's address doesn't exist, is inactive, or has a typo.

Fix: Double-check the address for typos and confirm it's active before resending.
 

You're seeing an unexpected spike in bounce messages

Problem: You're getting far more bounce notifications than usual, without sending more email yourself.

Cause: Your account may be compromised and used to send spam without your knowledge.

Fix: Change your password immediately
 

You can't send any more emails

Problem: Sending is paused and new emails won't go out.

Cause: You've reached your hourly or daily bounce limit.

Fix: Wait for the limit to reset, and clean up your recipient list before sending again.