Creating Item Attachments with the EWS Managed API with Powershell

Item Attachments in EWS allow you to create an Attachment that is of a Rich Exchange type such as an EmailMessage, Task, Post, Contact etc or even your own custom form if your using these. Although one thing you can't do with an Item attachment is attach an existing Exchange Item.

To use ItemAttachments in Powershell you need to use reflection in .NET as it involves invoking a Generic Method which is not that straight forward in Powershell.

The following is an example of creating a Task as an Item Attachment in Powershell using reflection

$mail = New-Object Microsoft.Exchange.WebServices.Data.EmailMessage($service);
$AtColtype = ("Microsoft.Exchange.WebServices.Data.AttachmentCollection") -as "Type"
$Tasktype = ("Microsoft.Exchange.WebServices.Data.Task") -as "Type"
$methodInf = $AtColtype.GetMethod("AddItemAttachment");
$AddItmAttachMethod = $methodInf.MakeGenericMethod($Tasktype);
$TaskAttachment = $AddItmAttachMethod.Invoke($mail.Attachments,$null);
$TaskAttachment.Item.Subject = "Mondays Task"
$TaskAttachment.Item.StartDate = (Get-Date)
$TaskAttachment.Item.DueDate = (Get-Date).AddDays(7)
$TaskAttachment.Name = "Mondays Task"
$mail.Subject = "See the Attached Task"
$mail.ToRecipients.Add("user@domain.com")
$mail.SendAndSaveCopy()

The MailboxConcurrency limit and using Batching in the Microsoft Graph API

If your getting an error such as Application is over its MailboxConcurrency limit while using the Microsoft Graph API this post may help you understand why. Background The Mailbox concurrency limit when your using the Graph API is 4 as per https://docs.microsoft.com/en-us/graph/throttling#outlook-service-limits . This is evaluated for each app ID and mailbox combination so this means you can have different apps running under the same credentials and the poor behavior of one won't cause the other to be throttled. If you compared that to EWS you could have up to 27 concurrent connections but they are shared across all apps on a first come first served basis. Batching Batching in the Graph API is a way of combining multiple requests into a single HTTP request. Batching in the Exchange Mail API's EWS and MAPI has been around for a long time and its common, for email Apps to process large numbers of smaller items for a variety of reasons. Batching in the Gr...

Sending a Message in Exchange Online via REST from an Arduino MKR1000

This is part 2 of my MKR1000 article, in this previous post I looked at sending a Message via EWS using Basic Authentication. In this Post I'll look at using the new Outlook REST API which requires using OAuth authentication to get an Access Token. The prerequisites for this sketch are the same as in the other post with the addition of the ArduinoJson library https://github.com/bblanchon/ArduinoJson which is used to parse the Authentication Results to extract the Access Token. Also the SSL certificates for the login.windows.net and outlook.office365.com need to be uploaded to the devices using the wifi101 Firmware updater. To use Token Authentication you need to register an Application in Azure https://msdn.microsoft.com/en-us/office/office365/howto/add-common-consent-manually with the Mail.Send permission. The application should be a Native Client app that use the Out of Band Callback urn:ietf:wg:oauth:2.0:oob. You ...

How to test SMTP using Opportunistic TLS with Powershell and grab the public certificate a SMTP server is using

Most email services these day employ Opportunistic TLS when trying to send Messages which means that wherever possible the Messages will be encrypted rather then the plain text legacy of SMTP. This method was defined in RFC 3207 "SMTP Service Extension for Secure SMTP over Transport Layer Security" and there's a quite a good explanation of Opportunistic TLS on Wikipedia https://en.wikipedia.org/wiki/Opportunistic_TLS . This is used for both Server to Server (eg MTA to MTA) and Client to server (Eg a Message client like Outlook which acts as a MSA) the later being generally Authenticated. Basically it allows you to have a normal plain text SMTP conversation that is then upgraded to TLS using the STARTTLS verb. Not all servers will support this verb so if its not supported then a message is just sent as Plain text. TLS relies on PKI certificates and the administrative issue s that come around certificate management like expired certificates which is why ...

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