Plain Text emails are not converted to HTML format and no signature is appended

Scenario:

You have enabled the feature Convert Plain Text messages to HTML before applying signature so that all messages are delivered in HTML format with a HTML signature appended.

Error: Method not found: 'Void Microsoft.Exchange.Data.Transport.Email.EmailMessage.Normalize()'.

Information: System.MissingMethodException: Method not found: 'Void Microsoft.Exchange.Data.Transport.Email.EmailMessage.Normalize()'.

at Exclaimer.Messaging.Transport.E2007.Converters.TnefBodyConverter.Convert(BodyFormat targetFormat, IConvertibleMessageOptions options)

at Exclaimer.Connectors.MailRules.Disclaimers.Workhorse.PerformMessageConversion(IEnvelope envelope)

at Exclaimer.Messaging.TemplateIntegration.DisclaimerWorkhorse`1.ApplyDisclaimer(IEnvelope envelope, IMessage outputMessage, Action`1 imprintIntializer, Boolean dontAddIfPresent)

at Exclaimer.Connectors.MailRules.Disclaimers.Implementation.ApplySubmittedPolicy(PipelineSubmittedMessage message, SubmittedMessageEventArgs args)

at Exclaimer.Connectors.MailRules.Implementation.ApplyPolicy(CapabilityImplementation capabilityImplementation, PipelineOperand operand, PipelineSubmissionArgs args)

at Exclaimer.PolicyProcessingEngine.Pipeline.ProcessingPipeline.ApplyPolicy(PolicyImplementation policyImplementation, PipelineOperand operand, PipelineSubmissionArgs args)

at Exclaimer.PolicyProcessingEngine.Pipeline.ProcessingPipeline.ProcessPolicy(PolicyImplementation policyImplementation, PipelineOperand operand, PipelineSubmissionArgs args)

at Exclaimer.PolicyProcessingEngine.Pipeline.ProcessingPipeline.Process(PipelineOperand operand, PolicyImplementation startPoint, PipelineSubmissionArgs args)


Resolution:

This problem has been resolved in Cumulative Update 8 (and higher) for Microsoft Exchange Server 2013.

Cumulative Update 8 Exchange Server 2013 can be downloaded from here.

Alternatively, disabling the feature Convert Plain Text messages to HTML before applying signature will also prevent the error. However plain text messages will be delivered with a plain text signature appended.