Using PowerShell and EWS to monitor a mailbox

I support a suite of application services that implement our ITIL processes. One of the functions allows users to create trouble tickets by sending a specially crafted email message to a specific email address. The application has a service that polls that mailbox once a minute to retrieve those messages and create new Incidents. Periodically, that email polling service stops working causing messages to queue up in the mailbox. The process is still running and providing other functions but it is no longer processing the inbound messages. We have monitoring on the system to watch that service and alert us when it hangs or crashes. However, since the service is still running, we never get alerted.

I needed another way to monitor for this problem. What if I could create a script that would check the mailbox to see if there were any messages in the Inbox that had arrived more than a few minutes ago? Since the service polled the mailbox every minute, any message more than five minutes old would indicate that the polling service had stopped functioning. But how can you read the Inbox?

In the past, I have used VBScript to automate Outlook and manage email on my desktop. However, I didn’t want to install Outlook on the server. Installing Outlook incurs licensing costs and is way more overhead than I really need. That also means that I need to manage patching for Outlook and other Office components on a server which we don’t normally do in our environment. Searching the internet I found some scriptable POP3 and IMAP clients. Some were commercial and some open source. But the cost of these options (in money and learning curve) was too high and the supportability was questionable.

We use Microsoft Exchange for our email services. I know that PowerShell is now the preferred method for most management tasks in Exchange. This led me to search for Exchange PowerShell options.

Enter Exchange Web Services (EWS) and its friendly.NET managed API. Installing and using the EWS Managed API is simple. It can be installed on any Windows machine and does not require any other Exchange components. Simply download the MSI package and install it.

• Download the Microsoft Exchange Web Services Managed API 2.2 from: http://www.microsoft.com/en-us/download/details.aspx?id=42951
• See the EWS Managed API reference at: https://docs.microsoft.com/dotnet/api/microsoft.exchange.webservices.data.emailmessage?view=exchange-ews-api

I am running this script as a scheduled task on Window Server 2008 R2. The scheduled task runs once per hour and is configured to run with domain credentials that have access to the target mailbox. The script uses EWS to access the mailbox and check for stale messages. It also uses Net.Mail.SmtpClient to send alert messages. I could have used EWS to send the alert message but Net.Mail.SmtpClient is so much easier to use.

param($mailboxName = "new-tickets@contoso.com",
$smtpServerName = "smtp.contoso.com",
$emailFrom = "monitorservice@contoso.com",
$emailTo = "support@contoso.com"
)

# Load the EWS Managed API
Add-Type -Path "C:\Program Files\Microsoft\Exchange\Web Services\2.2\Microsoft.Exchange.WebServices.dll"

try {
  $Exchange2007SP1 = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2007_SP1
  $Exchange2010    = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010
  $Exchange2010SP1 = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010_SP1
  $Exchange2010SP2 = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2010_SP2
  $Exchange2013    = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2013
  $Exchange2013SP1 = [Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2013_SP1

  # create EWS Service object for the target mailbox name
  $exchangeService = New-Object -TypeName Microsoft.Exchange.WebServices.Data.ExchangeService -ArgumentList $Exchange2010SP2
  $exchangeService.UseDefaultCredentials = $true
  $exchangeService.AutodiscoverUrl($mailboxName)

  # bind to the Inbox folder of the target mailbox
  $inboxFolderName = [Microsoft.Exchange.WebServices.Data.WellKnownFolderName]::Inbox
  $inboxFolder = [Microsoft.Exchange.WebServices.Data.Folder]::Bind($exchangeService,$inboxFolderName)

  # Optional: reduce the query overhead by viewing the inbox 10 items at a time
  $itemView = New-Object -TypeName Microsoft.Exchange.WebServices.Data.ItemView -ArgumentList 10
  # search the mailbox for messages older than 15 minutes
  $dateTimeItem = [Microsoft.Exchange.WebServices.Data.ItemSchema]::DateTimeReceived
  $15MinutesAgo = (Get-Date).AddMinutes(-15)
  $searchFilter = New-Object -TypeName Microsoft.Exchange.WebServices.Data.SearchFilter+IsLessThanOrEqualTo -ArgumentList $dateTimeItem,$15MinutesAgo
  $foundItems = $exchangeService.FindItems($inboxFolder.Id,$searchFilter,$itemView)

  # report the results via email and Application event log
  $entryType = "Information"
  $messageBody = "Self-service mailbox scan completed at {0}.`r`n" -f (get-date -format "MM/dd/yyyy hh:mm:ss")
  if ($foundItems.TotalCount -ne 0) {
  $entryType = "Warning"
  $subject = "Self-service mailbox hung"
  $messageBody  = "Inbox has {0} message(s) that are more than 15 minutes old.`r`n" -f $foundItems.TotalCount
  $messageBody += "Inbox has {0} message(s) total.`r`n`r`n" -f $inboxFolder.TotalCount
  $messageBody += "Please restart the Email Engine on SERVER01`r`n"
  $messageBody += "Self-service mailbox scan completed at {0}.`r`n" -f (get-date -format "MM/dd/yyyy hh:mm:ss")
  $messageBody += "Script run from $env:computername`r`n"
  $smtpClient = New-Object -TypeName Net.Mail.SmtpClient -ArgumentList $smtpServerName
  $smtpClient.Send($emailFrom, $emailTo, $subject, $messageBody)
  }
  Write-EventLog -LogName "Application" -Source "Application" -EventId 1 -Category 4 -EntryType $entryType -Message $messageBody
}
catch
{
  $entryType = "Error"
  $subject = "Error in mailbox monitor script"
  $messageBody = "{0}`r`n{1}" -f $_.Exception.Message,$_.InvocationInfo.PositionMessage
  Write-EventLog -LogName "Application" -Source "Application" -EventId 1 -Category 4 -EntryType $entryType -Message $messageBody
  $smtpClient = New-Object -TypeName Net.Mail.SmtpClient -ArgumentList $smtpServerName
  $smtpClient.Send($emailFrom, $emailTo, $subject, $messageBody)
}

About Sean Wheeler

I am an experienced IT technologist specializing in optimizing user experiences, providing best-in-class support and developing creative solutions. I script therefore I am. I build tools to improve troubleshooting and gather supporting data.

‹ Fun with Regular Expressions

Throwback Thursday – Windows IT Pro Magazine ›

Tagged with: ews, exchange web services, powershell
Posted in Scripting