Symptoms

You may face the following issue with notifications from "SmartForms Client Event" task: a task is assigned but there is no notification received by destination user. In Windows Application log following error message is being logged:
 

"61007 Permanent failure sending message SmartActionTask Notification: System.FormatException: The specified string is not in the form required for an e-mail address. at System.Net.Mail.MailAddressParser.ParseAddress(String data, Boolean expectMultipleAddresses, Int32and index) at System.Net.Mail.MailAddress..ctor(String address, String displayName, Encoding displayNameEncoding) at SourceCode.MessageBus.Ews.Destination.EwsMessageDestination.GetEmail(AlternativeCollection alternativeCollection) at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext() at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext() at System.Linq.Enumerable.Any.TSource](IEnumerable`1 source) at SourceCode.MessageBus.Ews.Destination.EwsMessageDestination.CanSend(MessageExtendedInformation info) at SourceCode.MessageBus.Ews.Destination.EwsMessageDestination.Send(String title, MessageExtendedInformation extended, IEnumerable`1 attachments, MessageBodyReadera] messageBodies) at SourceCode.MessageBus.Server.MessageBusRuntime.SourceCode.MessageBus.IMessageDestination.Send(String title, MessageExtendedInformation extended, IEnumerable`1 attachments, MessageBodyReadera] messageBodies)".

The issue occurs only for some particular user or subset of users and for other users notifications are working fine.
 

Diagnoses

This is known issue with K2 Host Server Notifications in K2 4.6.5/4.6.6 which was resolved in 4.6.8:

"A Client event notification would fail when the URM received a property or a name without a value. The URM server requested data from Active Directory (AD), and AD would return the data, but if an error occurs in AD, a SCNULL would be returned and thus inserted into the database. A property in the Identity.Identity table would return something like: <item name="" value="_scnull_" />. This caused the associated XML not to be formed correctly, and thus the notification would not run."

See "K2 blackpearl 4.6.8 Resolved Issues List" for details.

Coldfix is available for K2 4.6.5/4.6.6 upon request.
 

Resolution

Consider upgrade to 4.6.8 or newer version or, alternatively, contact K2 support to obtain coldfix for this issue for earlier versions of K2.