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Error codes

Learn more about error codes and how to resolve them.

SDK functions that return an error include an error code in the type attribute – a unique short string that is a brief explanation of the error. These codes play a role in our recommended error handling techniques.

Below is a list of possible error codes, along with additional information about how to resolve them. For convenience, every Error object links to their to this page in its docs attribute.


Address is invalid. Make sure address is syntax correct. Check error's cause for the underlying error. See address formatting for correct address formatting.


Identity has expired. Check the identity provider settings. Owner of the identity must renew domain to continue using it for messaging.


Identity is not found. Check address exists on supplied identity provider. When searching for name service providers check name is registered and resolves to the default protocol address.


Identity provider does not support address. Although identity provider is valid and address MAY be valid, Mailchain does not support this address. Check supported addresses.


Identity provider is not support. Check list of supported identity providers.


Failed calling messaging key contract or contract response is invalid. Check your connection, then try again.


Messaging key proof verification failed. The SDK will not use the messaging key for this address.


Messaging key is not yet registered. Register messaging key for address then retry.


Failed when performing checks before preparing a mail for sending. Check the error's message attribute for further information on what check failed.


Before sending a mail, the SDK prepares each distributions for the recipients. One or more distributions failed to prepare. Check the error's failures attribute for the failed distributions and corresponding errors.


Mailchain only supports certain protocols. Check you are using the latest version of the SDK and the protocol is supported then try again.


Before preparing a mail to send, the SDK resolves all addresses in the from, to, cc and bcc fields. One or more of these addresses failed to resolve. Check the error's failures attribute for the failed addresses and corresponding errors.


Delivery requests are sent to each recipient in the to, cc and bcc fields. One or more delivery requests failed to send. Check the error's failures attribute for the failed delivery requests and their corresponding errors.


The from address messaging key is incorrect. Check the sender messaging key matches, the latest entry in the the key registry for the from address.


An expected error occurred. Check error's message for more information and cause for the underlying error.