Use this article when a transaction fails, a recipient does not receive a notification, a signed document is not distributed, or the Log shows a delivery or signing error.
Before you start
A transaction can contain one signer, several signers, or several signer groups.
If an advanced signing flow has been added, the transaction can require documents to be signed in a specific order. This means that one step in the signing flow may depend on a previous step being completed first.
A transaction can also have several signers in the same group, even if no advanced signing flow has been added. In that case, the signers are grouped together, but this does not necessarily mean that the transaction follows a step-by-step signing order.
Signing flow also shows the current status of each signer. Signers can have different statuses in the signing flow, even if no advanced signing flow has been added.
This is important when you review errors, because Addo Sign has more than one log view:
Use Transaction details → Log when you need to review events for one specific signer
Use Signing details → Log when you need to review events for the full transaction, including all signers, groups, steps, and distribution events
A transaction will often have the status Failed when an error occurs, but not all errors stop the transaction. A transaction may still show a status such as Started or Completed even if an error is recorded in the log.
Which log should you check?
Check Transaction details → Log when the issue concerns one specific signer.
Examples:
One signer did not receive the notification
One signer’s e-mail address failed
One signer entered incorrect information too many times
One signer did not identify themselves
One signer did not complete their part of the signing flow
Check Signing details → Log when the issue concerns the full transaction.
Examples:
The signed documents were not distributed
The transaction failed after one or more signing steps
You need to review all signers in one timeline
You need to check distribution events after completion
You need to understand the overall transaction flow
💡Tip: Start by reviewing Signing flow if the transaction has several signers, signer groups, steps, or different signer statuses.
If the transaction uses advanced signing flow, Signing flow can also help you understand the required signing order.
Then use the relevant log:
Use Transaction details → Log for the affected signer
Use Signing details → Log for the full transaction timeline
Signing flow can show several groups and steps. If an advanced signing flow is used, the transaction may need to be signed in a specific order.
Signing flow shows each signer’s current status. Signers can have different statuses, even if no advanced signing flow has been added.
Find error messages in the log
Go to Overview.
Open the relevant transaction.
Review Signing flow if the transaction has several signers, signer groups, steps, or different signer statuses.
To review events for one signer, select the signer and open Transaction details → Log.
To review events for the full transaction, open Signing details → Log.
Find the error message in the timeline.
Use Transaction details → Log to review events for a specific signer.
Use Signing details → Log to review events for the full transaction.
Copy the exact error message if you need to contact Addo Sign Support.
How to use this article
Find the error message that matches the text shown in the Log.
Each section explains:
What the error means
Why it can happen
What you can do
The full error message or the most common version of it
Some error messages include additional text from the recipient’s mail server or from Digital Post. The exact wording can vary, but the recommended troubleshooting steps are usually the same.
Error types in the log
Most error messages appear either when Addo Sign sends the notification to the recipient, or when Addo Sign distributes the signed document after the signing flow has been completed.
The error message can come from Addo Sign, the recipient’s mail server, Digital Post, or the signing flow itself.
SMTP error codes can help identify whether a delivery issue is related to the recipient address, mailbox status, mail system, network, delivery protocol, message content, or security and policy settings.
Document distribution errors
Document distribution errors can occur after the signing flow has been completed, when Addo Sign tries to distribute the signed document.
These errors are usually shown in Signing details → Log, because document distribution happens at transaction level and not only for one specific signer.
An error occurred while distributing the document
What does it mean?
This error means that Addo Sign could not distribute the signed document after the transaction was completed.
The signing itself may have been completed, but the signed document could not be sent through the selected distribution method.
Why does it happen?
This can happen if the document is not compatible with the selected distribution method.
Common causes include:
The PDF contains interactive form fields
The PDF contains embedded URLs or data fields
The PDF contains pages with different sizes or dimensions
The document does not meet the requirements for the selected distribution method
The document does not meet Digital Post validation requirements, if Digital Post was used
What can you do?
First, check whether the transaction is completed and whether the signed document can be downloaded from Overview.
If the signed document is available, you can download it and distribute it through another approved method.
To prevent the issue from happening again, check the original document before sending a new transaction.
Make sure the document is:
Saved as a flat PDF
Free of interactive form elements
Free of embedded URLs or data fields
Using consistent page sizes and dimensions
Compatible with the selected distribution method
If the document must be sent through Digital Post, make sure the document follows the relevant Digital Post requirements before sending.
Full error message
An error occurred while distributing the document.
E-mail notification and delivery errors
Several e-mail delivery errors start with this message:
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification.
What does it mean?
This means Addo Sign tried to send a notification or document message, but the delivery failed.
Why does it happen?
The exact reason is usually shown after the message.
What can you do?
If the transaction has failed because the recipient’s e-mail address is incorrect, inactive, or no longer in use, update and save the e-mail address on the failed transaction before reactivating it. This ensures that the next notification is sent to the correct address.
If the transaction is still Started and the recipient details are correct, you can resend the notification manually if the option is available.
Recipient not found by SMTP address lookup
What does it mean?
The recipient’s e-mail address could not be found by the recipient’s mail server.
The server tried to look up the address, but it could not find a valid mailbox.
Why does it happen?
Common causes include:
A spelling mistake in the e-mail address
The e-mail address is no longer active
The domain is incorrect or outdated, for example @gmial.com instead of @gmail.com
What can you do?
Check the e-mail address with the recipient.
If the address is incorrect, inactive, or no longer in use, update and save the e-mail address on the failed transaction before reactivating it.
If the transaction is still Started, update the recipient details and send a new notification manually if needed.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: 550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup.
Unknown recipient
What does it mean?
The recipient’s e-mail address is not recognized by the recipient’s mail server.
The message cannot be delivered because the address is invalid, does not exist, or has been deleted or deactivated.
Why does it happen?
Common causes include:
A typo in the e-mail address
The e-mail account no longer exists
The domain is incorrect or inactive
What can you do?
Confirm the correct e-mail address with the recipient.
If the address is incorrect, inactive, or no longer in use, update and save the e-mail address on the failed transaction before reactivating it.
If the transaction is still Started, update the recipient details and send a new notification manually if needed.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: 550 5.1.1 Unknown recipient.
The email account that you tried to reach does not exist
What does it mean?
The e-mail address does not exist.
The recipient’s mail server attempted delivery, but could not find a valid mailbox for the address.
Why does it happen?
Common causes include:
A typo in the e-mail address
A misspelled domain or username
The e-mail account has been deleted
The e-mail account never existed
Extra spaces or formatting issues in the e-mail field
What can you do?
Check the e-mail address carefully.
Remove unnecessary spaces and confirm the address with the recipient.
If the address is incorrect, inactive, or no longer in use, update and save the e-mail address on the failed transaction before reactivating it.
If the transaction is still Started, update the recipient details and send a new notification manually if needed.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: 550 5.1.1 The email account that you tried to reach does not exist.
Mailbox unavailable
What does it mean?
The e-mail could not be delivered because the recipient’s mailbox is not available.
This means the e-mail address may exist, but the mailbox cannot receive the message at the time of delivery.
Why does it happen?
Common causes include:
The recipient’s mailbox is full
The mailbox has been suspended, disabled, or deleted
The recipient’s mail server is temporarily unavailable
The address is valid, but misconfigured or blocked
What can you do?
Ask the recipient to check whether their mailbox is active and able to receive messages.
If the issue is temporary, try again later or resend the notification if the transaction still allows it.
If the mailbox is disabled, deleted, or no longer used, ask the recipient for an alternative e-mail address. If the transaction has failed, update and save the e-mail address before reactivating it.
Full error messages
1) Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: 550 5.5.0 Requested action not taken: mailbox unavailable.
2) Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: 550 Requested action not taken: mailbox unavailable.
The recipient’s inbox is out of storage space
What does it mean?
The recipient cannot receive new e-mails because their mailbox has run out of storage space.
Until space is made available, new e-mails may be rejected.
Why does it happen?
Common causes include:
The recipient’s mailbox has exceeded its storage limit
The recipient’s e-mail provider is temporarily blocking new messages until space is available
What can you do?
Ask the recipient to clear space in their inbox by deleting or archiving e-mails.
If the recipient cannot make space available, ask for an alternative e-mail address. If the transaction has failed, update and save the e-mail address before reactivating it.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: 452 4.2.2 The recipient's inbox is out of storage space.
E-mail server connection errors
Error dialing remote address: i/o timeout
What does it mean?
Addo Sign tried to send an e-mail, but the recipient’s e-mail server did not respond in time.
The delivery attempt timed out. You can think of it as trying to call someone, but the call keeps ringing and no one answers.
Why does it happen?
Common causes include:
The recipient’s e-mail server is down or not responding
The recipient’s mail system has a temporary network issue
The recipient’s mail system blocks certain e-mail traffic
The recipient’s mail system blocks traffic on specific ports, for example port 25
What can you do?
Check that the e-mail address is correct.
Try again later, as the issue may be temporary.
If the issue continues, ask the recipient for an alternative e-mail address or ask the recipient to contact their IT department.
If you use an alternative e-mail address on a failed transaction, update and save the e-mail address before reactivating the transaction.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: error dialing remote address: dial tcp ***.***.*.**:*->***.***.***.**:**: i/o timeout.
E-mail blocked or rejected
Bounced Address
What does it mean?
The e-mail could not be delivered and was returned by the recipient’s mail server.
In some cases, this happens because the recipient’s mail system blocks e-mails from Addo Sign.
Why does it happen?
Common causes include:
The e-mail was blocked by the recipient’s mail system
The recipient’s organization has strict e-mail rules
The recipient’s organization has blocked the Addo Sign sending domain
What can you do?
Ask the recipient or the recipient’s IT department to allow e-mails from:
After the recipient has allowed e-mails from Addo Sign, contact Addo Sign Support and ask whether the e-mail address needs to be removed from the bounced list.
If the recipient does not allow e-mails from Addo Sign first, the address may return to the bounced list.
If you choose to use another e-mail address instead, update and save the e-mail address on the failed transaction before reactivating it.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: Bounced Address.
Recipient address rejected: Access denied
What does it mean?
The e-mail was blocked or rejected by the recipient’s mail server.
The recipient’s organization refused to accept the message, often because of security or filtering settings.
Why does it happen?
Common causes include:
The recipient’s mail server does not allow messages from the sender or domain
The recipient’s organization uses strict filtering rules
The recipient’s domain is configured to reject certain external messages
What can you do?
Ask the recipient or the recipient’s IT department to allow e-mails from:
After this has been done, resend the notification if the transaction still allows it.
If the transaction has failed and you decide to use another e-mail address, update and save the e-mail address before reactivating the transaction.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: 550 5.4.1 Recipient address rejected: Access denied.
Spam Reporting Address
What does it mean?
The recipient’s e-mail system has flagged the sending address as potential spam.
As a result, the message was rejected or blocked.
Why does it happen?
Common causes include:
The recipient or their e-mail provider marked previous messages as spam
The sending address or domain has been flagged by the recipient’s mail filters
The recipient’s spam filter settings are too strict
What can you do?
Ask the recipient to:
Check their spam or junk folder
Allow e-mails from [email protected]
Contact their IT department if the message is blocked by internal mail rules
If the issue continues, contact Addo Sign Support to check whether the address is listed as bounced or blocked.
After the issue is resolved, reactivate the transaction or resend the notification if available.
If you choose to use another e-mail address instead, update and save the e-mail address on the failed transaction before reactivating it.
Full error message
Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: Spam Reporting Address.
Digital Post and CPR errors
Contact with cpr ********** does not exist
What does it mean?
Digital Post could not find a valid recipient linked to the CPR number used for the transaction.
As a result, the document could not be delivered through Digital Post.
Why does it happen?
Common causes include:
The CPR number is invalid or mistyped
The recipient has opted out of Digital Post
The recipient is legally exempt from Digital Post, for example due to age or protected status
The CPR number belongs to a person who cannot receive this type of message
What can you do?
Confirm the CPR number with the recipient.
Check whether the recipient is registered with Digital Post and able to receive digital mail.
If delivery through Digital Post is not possible, use another approved delivery method, such as e-mail or secure file transfer.
You can also download the signed document manually and send it through another approved channel.
If the transaction must be reactivated or resent, correct the CPR number or delivery method before doing so.
Addo Sign also offers CPR validation, which can help validate CPR numbers before sending.
Full error message
1) Possible problem with delivering notification. Please verify recipient details are correct and resend the notification. Error message: Contact with cpr ********** does not exist.
2) Error message: End user not recognised.
This error may occur when sending to e-Boks via address if e-Boks cannot uniquely identify the recipient. This can be caused by missing consent for address lookup in e-Boks, name or address protection, or because the entered information does not match the registered information.
Login and authentication errors
Too Many Failed Login Attempts
What does it mean?
The signer entered incorrect information too many times when trying to access or identify themselves in the signing flow.
To protect the transaction, Addo Sign blocks further attempts and marks the transaction as failed.
Why does it happen?
Common causes include:
The signer entered the wrong verification code repeatedly
The signer used the wrong login or identification method
The signer entered an incorrect SMS code, password, or identification information several times
The system triggered a security lockout to prevent unauthorized access
What can you do?
Contact the signer and confirm that they are using the correct login or identification method, for example MitID, SMS code, or password.
Make sure the signer understands the required steps before trying again.
Reactivate the transaction when the signer is ready to try again.
Full error message
Transaction failed because signer attempted to login unsuccessfully too many times.
Before contacting support
Before contacting Addo Sign Support, you should check:
Whether you reviewed the correct log
Whether the issue concerns one signer or the full transaction
Whether the transaction uses an advanced signing flow
Whether several signers are connected to the same group
Whether the transaction status is Failed, Started, or Completed
Whether the Log contains an exact error message
Whether the recipient details were corrected and saved before the transaction was reactivated or resent
Whether the e-mail address is incorrect, inactive, no longer in use, blocked, or unavailable
Whether an alternative e-mail address was used
Whether the recipient or their IT department has allowed e-mails from [email protected], if the error indicates that the message was blocked or rejected
Whether the recipient’s e-mail address, phone number, CPR number, or delivery method is correct
Whether the recipient’s mailbox or mail server may be blocking the message
Whether the recipient has checked their spam or junk folder
Whether the transaction can be corrected, reactivated, or resent
Whether the signed document can be downloaded and distributed by another approved method
If you still need help, include:
Transaction ID
Signing ID
Current transaction status
Recipient name and e-mail address, phone number, or CPR number
Delivery method used
Exact error message from the Log
Screenshot of the relevant log entry
Whether the error was found in Transaction details → Log or Signing details → Log
Whether the transaction uses an advanced signing flow
Which signer, group, or step the issue concerns
Whether the recipient details were updated before reactivation
The updated e-mail address, if an alternative address was used