Kaleidoscope Connect: Error and Warning Dictionary

When sending an SMS or email campaign, there are several factors that could cause a message to go undelivered to a contact. To ensure the highest delivery rate, follow our best practices for SMS and Email.


If a message is unable to be delivered to a contact, you will see an error code appear next to that contact on your campaign Results page.


Below is a list of the most common error codes that occur when sending a campaign:

Don't see your error code below? You can view the entire list of error codes here.


Common SMS Error Messages


ERROR - 30007

Message filtered

Your message content was flagged as going against carrier guidelines. Your message was filtered (blocked) by the contact's carrier. This may be done for violating carrier rules or regulations.

These carrier filters are used to block abusive traffic, as well as to enforce rules or regulations about what types of messaging are allowed to that country or mobile network.


Possible Causes

  • Your message was identified as spam or unwanted messaging by our message filtering system
  • Your message was flagged as objectionable and blocked by a wireless carrier

Possible Solutions

  • Ensure that your messages clearly identify who is sending the message, and how to opt-out. If you are contacting the same recipients multiple times per month, you do not need to provide opt-out instructions in every message, but you must do it at least once per month.
    • Suggested language: "Reply STOP to no longer receive messages from us."
  • URL shortening: Do not send links that have been shortened using shared public URL shorteners, such as TinyUrl or free Bitly links.
  • If possible, when sending URLs/links in your messages, use domains that you control.
  • Don’t use emojis, or unnecessary special characters/capitalization, and watch your grammar and spelling.  Typically, these messages are structured in a way to attempt to evade detection of unwanted messaging, and your messages will be filtered.

ERROR - 30003 or 30005

Unreachable destination handset

The destination handset you are trying to reach is switched off or otherwise unavailable.


Possible Causes

  • The destination handset you are trying to reach is switched off or otherwise unavailable.
  • The device you are trying to reach does not have sufficient signal
  • The device cannot receive SMS (for example, the phone number belongs to a landline)
  • There is an issue with the mobile carrier

Possible Solutions

The first step to troubleshooting this issue is to attempt to replicate the problems. Attempt to send another test message to this user.

If you see similar results, continue troubleshooting with the following checklist:

  • Is the destination device powered on?
  • Does the device have sufficient signal? If not power the device off, wait 30 seconds, and then power it back up.
  • Is the device connected to the home carrier's network? We cannot guarantee message delivery on devices roaming off-network.
  • Can the device receive non-Kaleidoscope SMS?
  • Can the device receive messages from another Kaleidoscope assigned number, or with a shorter one-credit body message?
  • Can other devices using the same mobile carrier receive your messages?

ERROR - 30006

Landline or unreachable carrier

Destination is a landline and incapable of receiving SMS, or is an unreachable destination carrier.


Possible Causes

  • The device is a landline that is unable to receive SMS messages

Possible Solutions

  • Is the destination device powered on?
  • Does the device have sufficient signal? If not power the device off, wait 30 seconds, and then power it back up.
  • Is the device connected to the home carrier's network? We cannot guarantee message delivery on devices roaming off-network.
  • Can the device receive non-Kaleidoscope SMS?
  • Can the device receive messages from another Kaleidoscope assigned number, or with a shorter one-credit body message?
  • Can other devices using the same mobile carrier receive your messages?

ERROR - 11200

HTTP retrieval failure

There was likely a connection failure between our SMS provider and Kaleidoscope. A connection failure will occur if no response is returned within 15 seconds time.

If you receive this error intermittently, try re-sending the message to the contact. If this error is more widespread, contact Kaleidoscope.


Common Email Error Messages


ERROR - 421

Message temporarily deferred

Messages are temporarily deferred because of recipient server policy - often it's because of too many messages or connections in too short of a timeframe. We continue to retry deferred messages for up to 72 hours.

Possible Solution

Consider temporarily sending less messages when this code is being returned because this could further delay your messages currently being tried. Reach out to Kaleidoscope Support.


ERROR - 451

Temporary local problem - please try later

The message simply failed, usually due to a far-end server error. We continue to retry messages for up to 72 hours.


ERROR - 551

User does not exist

The intended mailbox does not exist on this recipient server. Remove these addresses from your list.


ERROR - 552

This message is larger than the current system limit or the recipient’s mailbox is full

The recipient's mailbox has exceeded its storage limits. We don't resend messages with this error code because this is usually a sign this is an abandoned email.

Possible Solution

Create a shorter message body or remove attachments and try sending it again.


ERROR - 553

Invalid/inactive user

The message was refused because the mailbox name is either malformed or does not exist. Remove these addresses from your list.


ERROR - 554

Mail refused

This is a default response that can be caused by a lot of issues. There is often a human readable portion of this error that gives more detailed information, but if not, remove these addresses from your list.