not supported calendar message.ics when sending from third party system (SAP HR)

Question

I know that this is an quite obvious issue when browsing the internet or msdn forum but it seems not in my case. Since my mailbox is on Exchange Online messages arriving from our SAP HR system are labeled as IPM.Note.NotSupportedICal and the attachement is renamed to "not supported calendar message.ics" regardless in which client I received the message (I tried Outlook 365 and Outlook on the web). I am currently the only productive user on Exchange Online in our tenant because I'm the Exchange administrator and currently evaluating whether we have problems if mailboxes are on Exchange Online. Nevertheless I guess it would be the same for other mailboxes in Exo. The strange thing is, that messages that arrived in the mailbox while it was on Exchange OnPremise weren't marked as not supported. Here some screenshots:

Working because received while on Exchange OnPremise:

Content of attached ics file:

BEGIN:VCALENDAR
VERSION:2.0
METHOD:PUBLISH
BEGIN:VEVENT
UID:2604A02AA8071EDAA998DFFF4E534097
SUMMARY: Urlaub/Leave
DESCRIPTION: Der Kalendereintrag enthält die Daten Ihres Antrags vom 02.06.2020. Weitere Informationen entnehmen Sie bitte dem Mitarbeiterportal.\nThe calendar entry is about your request from 02.06.2020. Further information can be received in the Self Service Portal.
CLASS:PUBLIC
TRANSP:TRANSPARENT
DTSTART:20201109
DTEND:20201114
DTSTAMP:20201109
LOCATION:
X-MICROSOFT-CDO-BUSYSTATUS:OOF
END:VEVENT
END:VCALENDAR

Not working because received while on Exchange Online:

Content of attached ics file:

BEGIN:VCALENDAR
VERSION:2.0
METHOD:PUBLISH
BEGIN:VEVENT
UID:2604A02AA8071EDB82A80EB570E396E4
SUMMARY: Urlaub/Leave
DESCRIPTION: Der Kalendereintrag enthält die Daten Ihres Antrags vom 08.10.2020. Weitere Informationen entnehmen Sie bitte dem Mitarbeiterportal.\nThe calendar entry is about your request from 08.10.2020. Further information can be received in the Self Service Portal.
CLASS:PUBLIC
TRANSP:TRANSPARENT
DTSTART:20201125
DTEND:20201128
DTSTAMP:20201125
LOCATION:
X-MICROSOFT-CDO-BUSYSTATUS:OOF
END:VEVENT
END:VCALENDAR

As you can see there is no special recurring rule entry or something else and the content doesn't differ between Exo and OnPrem. It's just a simple ics file in both cases. Maybe Exchange on premise modifies the attachment without marking it as not supported!? In both cases the attachment can be opened and saved in calendar without issues. As the support couldn't help me so far maybe someone else can point me in the right direction to narrow down the issue. Saving the attachment and sending it via powershell the same way as the SAP system does does not reproduce the problem. I haven't found a way to reproduce the problem other than sending a mail from SAP, anyway.

Additional Information:

• Exchange 2016 CU18 on premise Hybrid configuration with centralized mail transport.
• Therefore send connetors to Exchange Online were automatically configured by Hybrid Configuration Wizard
• Mailflow in this case: SAP -> Receive Connector Exchange on premise -> Send connector on premise -> Exchange Online

Any hints welcome.
Thanks, Daniel.

Answer 1

I guess I found the problem. The method parameter in the smtp communication does not match the method in the ics file:

Obviously Exchange 2016 CU18 doesn't mind. Once I change it to match the one in the ics file (both "PUBLISH" for example) the message isn't marked as unsupported.

In addition I found the corresponding RFC text that confirms this:

https://tools.ietf.org/html/rfc6047#section-2.4

Maybe these findings help someone else.

Answer 2

Hi @Brase, Daniel ,
Has this error occurred before?

1. I saw you mentioned that you saving the attachment and sending it via powershell the same way as the SAP. What is the specific process?
2. According to the information you provide, the attachment can be downloaded and added to the calendar for normal use, indicating that the attachment can be used. Then the reason for the error may be when the attachment is sent to Exchange, because the original .ics file cannot be converted to an Outlook or Microsoft Exchange meeting type.
3. In order to exclude the error caused by the internal transmission of Exchange on-premise. Please try to send the calendar directly to Exchange online users.
4. According to my research the similar cases, I found that for meeting requests sent by .ics files, the address of the "ORGANIZAER" parameter needs to be the same as the "FROM" address, otherwise this error will occur. Does the third-party software you use involve this parameter? ? If involved, please check.
   In addition, considering that this problem only occurs when sent by a third-party software (SAP HR), it is recommended that you contact the provider to check whether a similar problem occurs. The following link is a link to the SAP forum. You can also try to see if any related problems occur.
   SAP Community
   Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

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Answer 3

Hi @Lucas Liu-MSFT ,

thanks for your reply. This issue occurs since I moved my mailbox to Exchange Online. Because I'm the first and only one on Exchange Online yet I can only say that on Exchange Online those mails were always marked as not supported. My mailbox was moved in late June this year. As you can see the not supported messages started at from point in time on:

You can ignore the messages without attachment because they are informational only.

To your other questions:

1. I tried to reproduce with following command: "Send-MailMessage -From <from address> -To <Exchange Online email address> -Subject Test -Cre
   dential $creds -SmtpServer <on premises Exchange server> -Attachments c:\temp\001.ics". 001.ics was saved from an email, that had been marked as unsupported. With this command I receive the email just as IPM-Note with an normal attachment named 001.ics. It seems that this is not a good condition to reproduce the issue because it's apparently only simliar but not the same way as sending by our SAP system.
2. I'm afraid you're right. But why it works on Exchange 2016? Doesn't Exchange 2016 convert messages with ics files to Outlook or Exchange meeting type?
3. I will try.
4. As you can see in the original post the ics files has no organizer property. It would be nice to know, what properties have to be provided at least in order to Exchange accept these files as supported. This would help a lot.

Meanwhile I captured the smtp stream of one of the emails that are not supported. Once I emulate the smtp communication with a telnet connection I can reproduce the issue and I am able to replace the base64 encoded part that represent the ics file. Therefore I'm able to test with different ics file content. I will update this thread to my findings accordingly.