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Error when trying to send emails with attachment in workflow


Error when trying to send emails with attachment in workflow

This article was created in response to a support issue logged with K2. The content may include typographical errors and may be revised at any time without notice. This article is not considered official documentation for K2 software and is provided "as is" with no warranties.
This article has been archived, and/or refers to legacy products, components or features. The content in this article is offered "as is" and will no longer be updated. Archived content is provided for reference purposes only. This content does not infer that the product, component or feature is supported, or that the product, component or feature will continue to function as described herein.


When workflow tries to send an email with an attachment, the workflow goes into an error state and the following error message appears:


"SourceCode.Workflow.Common.EWS: Autodiscover Failure: The Exchange Server is not available, the password is incorrect or the email address does not exist."


  • Workflow is able to send the email if  the email has no attachment
  • If you used ConnectionStringEditor to disable autodiscover for the Exchange connection string, the error still remains
  • HostServer logs show a mail send failure, with Exchange server returning a 501 not implemented error

Troubleshooting Steps

First check which version of K2 is being used, and what the version of the Exchange Server used in the K2 environment.


If it is on K2 4.7 and your Exchange Server version is 2010, then please note that K2 4.7 no longer supports Exchange Server 2010. For more information on this, please refer to the compatibility matrix.


When using K2 4.7 and Exchange Server 2010, you have only 2 options:

  1. Upgrade Exchange Server to 2013 or above.
  2. Reconfigure K2 to use SMTP instead of Exchange. Please note that as of 4.7, SmartActions only work with Exchange, so if you are currently using SmartActions, or you have plans to use SmartActions in the future, your only option is to upgrade your Exchange Server.
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Last update:
‎03-15-2022 04:12 AM
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