Any idea as to what this message means? We seem to get it random intervals on an email activity which breaks the entire workflow. Do run the workflow again right away and it works.
The reply is an Exchange response basically stating the Exchange service couldn't handle the request at the time. Engage the Exchange administrator for email server you're attempting to connect to, provide them several examples of the exact response you're getting, and the exact date/time/timezone you received it, and they should be able to vet through the logs and determine what's happening at that time and correct it. Based on forum discussions of this Exchange error, it can be a number of different things.
My thoughts on a workaround: assuming we're just sending mail, set up an IIS SMTP server on the workflow server locally and submit your messages there. Once Workflow has been able to complete an SMTP submission into an SMTP queue, you're good. The SMTP server, even if it attempts to deliver into the Exchange server, will retry, whereas Workflow won't. The goal here being, get it out of Workflow into the SMTP stream the first time, and then let normal SMTP message retrying handle any hiccups that are occurring in your Exchange environment.
Could you look in the activity error log and post the full error message?
Where exactly is that? I have checked the event viewer and the workflow admin console and there are no entires for that time (2:51).
Workflow Admin Console, under Monitoring\Error Logs\Current Error Logs\activity errors.log. Sometimes Windows won't pick up the Last Modified date correctly, so make sure to open the log and check.
Hmm, when I checked that log yesterday nothing was there. Must have taken a bit to catch up.
Message: <Exception handlingInstanceId="573b9d03-ef32-4009-9e8e-ec1ea4dda345">
<Description>An exception of type 'System.Exception' occurred and was caught.</Description>
<DateTime>2017-03-01 14:51:39Z</DateTime>
<ExceptionType>System.Exception, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType>
<Message>Error in processing. The server response was: 4.7.0 Timeout waiting for client input</Message>
<Source>Laserfiche.Workflow.Activity.Base</Source>
<HelpLink />
<Property name="ActivityName">Email_Email</Property>
<Property name="ActivityType">Laserfiche.Workflow.Activities.Email.EmailActivity</Property>
<Property name="InstanceId">42f4436a-821d-4c59-b101-e3d170cc52d3</Property>
<Property name="TargetSite">Void ProcessTaskQueueEvent(System.Workflow.ComponentModel.ActivityExecutionContext)</Property>
<Property name="HResult">-2146233088</Property>
<StackTrace> at Laserfiche.Workflow.Activities.TaskActivityBase.ProcessTaskQueueEvent(ActivityExecutionContext context)
at Laserfiche.Workflow.Activities.TaskActivityBase.OnEvent(Object sender, QueueEventArgs e)
at System.Workflow.ComponentModel.ActivityExecutorDelegateInfo`1.ActivityExecutorDelegateOperation.Run(IWorkflowCoreRuntime workflowCoreRuntime)
at System.Workflow.Runtime.Scheduler.Run()</StackTrace>
<additionalInfo>
<info name="MachineName" value="servername" />
<info name="TimeStamp" value="3/1/2017 8:51:39 PM" />
<info name="FullName" value="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<info name="AppDomainName" value="Laserfiche.Workflow.Service.exe" />
<info name="ThreadIdentity" value="" />
<info name="WindowsIdentity" value="accountname" />
</additionalInfo>
<InnerException>
<ExceptionType>System.Net.Mail.SmtpException, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType>
<Message>Error in processing. The server response was: 4.7.0 Timeout waiting for client input</Message>
<Source>System</Source>
<HelpLink />
<Property name="StatusCode">LocalErrorInProcessing</Property>
<Property name="EmailSyncLevel">1</Property>
<Property name="StartTime">3/1/2017 8:51:39 PM</Property>
<Property name="EndTime">3/1/2017 8:51:39 PM</Property>
<Property name="Duration">00:00:00.0312530</Property>
<Property name="InstanceId">42f4436a-821d-4c59-b101-e3d170cc52d3</Property>
<Property name="ActivityName">Email_Email</Property>
<Property name="Workflow">VATSInvoiceVerification</Property>
<Property name="ContextGuid">42f4436a-821d-4c59-b101-e3d170cc52d3</Property>
<Property name="TargetSite">Void CheckResponse(System.Net.Mail.SmtpStatusCode, System.String)</Property>
<Property name="HResult">-2146233088</Property>
<StackTrace> at System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response)
at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)
As Damon says below, it's a mail server error. I found this thread that indicates it can sometimes be caused by network errors. You're going to have to work with your Exchange and network administrators to track down the root cause.
You could also add that error to the Task Error handlers so Workflow retries rather than terminating.