Please accept our apology for a delayed response as we are busy in our monthly product release for Aspose.Email.
I was also able to observe this issue as you mentioned. Aspose.Email is not allowing to add multiple standard folders of the same type. However, adding multiple standard folders of the same type may also need modification where one retrieves the Predefined folder by its name such as “Contacts” as it would need differentiation between these. I have requested development team to provide their opinion in this regard and will update you as soon as there is some information available.
In order to investigate the possible implementation of mulitple standar folders with the same type, I have logged an investigation ticket in our issue tracking systme with issue id: NETWORKNET-33870. Development team will look into it and once I have any information available in this regard, I’ll update you here. Your patience till then is highly appreciated.
CreatePredefinedFolder method creates folders that are added by Outlook by default when it creates a new file. In other words, CreatePredefinedFolder method allows to create a minimum set of predefined folders, that will be used by Outlook by default. That’s why, AE throws exception.
In order to add one more folder for contacts for example, it is recommended to use the following code: