Bounced Email Guide
When sending email, you will occasionally receive a notification in DailyStory that your message bounced.
What is a bounced email
A bounced email is a notification from the recipient's email system informing the sender that the message has not been delivered (or another delivery problem occurred). The original message is said to have "bounced".
What causes email to bounce
There can be numerous causes that lead to an email server preventing delivery of your message:
- An email filter prevented delivery of your message
- The recipients inbox is full and is out of storage
- The email address no longer exists
- The amount of email sent to the domain it too high a volume in too short a time period
Types of bounces
There are two distinct types of bounces that can occur.
RecommendedIf you receive a high bounce rate on an email send DailyStory will throttle delivery of additional messages.
Soft Bounce
A temporary issue related to the recipient's email server preventing delivery.
- Code usually starts with "4xx"
Soft bounces usually resolve themselves. DailyStory will continue checking the status of a soft bounced email for up to 12 hours.
Hard Bounce
A permanent issue related to the recipient's email server.
- Message couldn't be delivered due to some sort of invalid, unchangeable, permanent reason
- Some are in your control and some are not (see below for tips for what is in your control)
- Code usually starts with "5xx"
To check your SPAM score (a numerical rating 0-10), you can use a free site like https://www.mail-tester.com/ to understand if your emails are at risk.
How to prevent bounced emails
There are several steps you can take to prevent emails from bouncing. And we recommend reading our detailed blog post for avoiding the junk folder and preventing bounced emails.
Use clean and verified data
It's important that you keep your email lists clean and up-to-date.
- Refrain from using unreliable contact lists
- Remove incorrect or old emails which affect your bounce rate
- Use a service such as NeverBounce to verify the deliverability of email addresses
Avoid common content SPAM triggers
There are number of known SPAM triggers that you can avoid.
- Avoid numerous exclamation points. This can trigger mail providers to block your email as SPAM.
- Use standard fonts and colors. Unrecognized fonts and colors can trigger your email as SPAM.
- Compress images and use the rule of thumb of 70% text and 30% images.
- Remove excessive links. Emails will be flagged as SPAM if there are more than 6 links.
Avoid common SPAM words and phrases
See our article Keyword blocklists: What they do and whether you should use them to access and download common SPAM keywords to avoid.
RecommendedAn acceptable bounce rate is between 2-5%. Anything over 5% suggests a problem you need to address and resolve. DailyStory report dashboards give you bounce % rates for individual emails and emails within a timeframe you can set.
Bounced status reports in DailyStory
When viewing bounced reports in DailyStory, you will see the type of bounce and the bounce code.

To see a complete list of your bounced contacts, navigate to Contacts > Search Contacts
from the Navigation Bar menu and select Bounced from the Status
field row.

Bounced contacts will not be reflected in saved segments numbers or appear in saved segment lists, so you cannot save this search as a segment. To work with your bounced list, create the search and then export the list.
Bounce code descriptions
Code | Description |
421 | service not available, closing transmission channel |
450 | Requested mail action not taken: mailbox unavailable (e.g., mailbox busy) |
451 | Requested action aborted: error in processing |
452 | Requested action not taken: insufficient system storage |
500 | The server could not recognize the command due to a syntax error. |
501 | A syntax error was encountered in command arguments. |
502 | This command is not implemented. |
503 | The server has encountered a bad sequence of commands. |
504 | A command parameter is not implemented. |
550 | User’s mailbox address is invalid |
551 | The recipient is not local to the server. |
552 | The action was aborted due to exceeded storage allocation. |
553 | The command was aborted because the mailbox name is invalid. |
554 | The transaction failed for some unstated reason. |
602 | Internal error code that messages bounced after attempts over 8 hours. |
Bounce and retry handling
DailyStory includes advanced logic for bounce/retry logic to automatically reset emails if a non-hard bounce error occurs.
For example, email recipients that return a bounce status due to:
- Inbox full
- Inbox over quota
- Inbox temporarily disabled
These and other codes - at DailyStory's discretion - will instead change the contacts do not contact until a date to a future date between 15-30 days out. This ensures the contact can cool down for a period of time prior to being eligible for a future email campaign.