Unknown MAPI properties

Dear Aspose team

We are using Aspose.Email to convert EML files. We started adding additional attachments to the messages we are converting and have noticed the following unknown properties have changed when we save the MapiMessage object to an MSG file. We are not touching these properties while constructing the MapiMessage. We are simply comparing the original version of the MSG files with the new version to rule out any regression. Are you able to provide any explanation of what these 3 properties do, please?

Property 1
Long Key: 2147549195
Hex Key: 0x8001000B

Property 2
Long Key: 2147614731
Hex Key: 0x8002000B

Property 3
Long Key: 2147680267
Hex Key:0x8003000B

Properties 2 and 3 are missing both PropertyTagName and Descriptor.name

Thank you for any information you can provide.

Hello @ml42,

It seems you are dealing with Named Properties, which do not have a persistent tag. The named property range generally starts above 0x8000. When you resave a message, the identifier may refer to a different property.

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Thank you, @margarita.samodurova, I understand it is expected then for these properties to potentially change when we make changes to the overall message.

@ml42 ,

Yes, that’s right. You’re welcome to ask any questions you have or for any assistance you might need.

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