RDCOMClient | R package allows users to invoke COM methods

First of all, there is no need to create a new Outlook Application instance each time in the loop:

You are interested in setting up the MailItem.FlagRequest property which returns or sets a string that indicates the requested action for a mail item. By default, a mail item is not marked with any flag and the default value for this property is the empty string.

I am not sure of a way to do this in R, but you should be able to do it in powershell.

I am very bad at powershell, but this at the very least gets all the properties and methods of an object:

Any SMTP client implemented in R will do the job. Check out this one: Rmailer

From their example:

You would need to retrieve a particular item from the Results collection and call MailItem.Reply or MailItem.ReplyAll instead of Application.CreateItem.

This does the trick. Looked up the VBA Code and converted it. Should be useful in the future.

Set the MailItem.DeferredDeliveryTime property - https://docs.microsoft.com/en-us/office/vba/api/outlook.mailitem.deferreddeliverytime

You don't need the MailModule object. Take a look at the live Outlook objects with OutlookSpy (click the Item button on the OutlookSpy ribbon).

I suspect that 44029.7004451092 is simply a fraction of the number of days since 1900. So, if you can access that number (I'm not sure how, as I don't have access to Outlook emails, but it shouldn't be too hard to access it from the object), then we can write a function to extract the time.

For example, assume you've extracted that .Data string: '44029.7004451092'.

We can pass that into a custom function. This function basically splits the string up into two parts. The first part is the day (i.e., 44029). That's where we get the date from. The second part is the series of digits after the period, which I'm assuming is meant to refer to the fraction of the day. (For example, 0.5 would be 12 pm.)

We can then just do some simple arithmetic to figure out how many hours, minutes and seconds are in that fraction, based on the number of seconds in a day. Then we wrap it all up, and return a POSIXct object.

R does not use period qualifiers to access underlying methods. However, periods are allowed in object names. So R is attempting to find a function named xlWbk.VBProject.VBComponents.Import().

While in VBA or VBS, period means accessing properties and attributes, in R you need to adjust with [[ or $ qualifiers. Hence, consider adjusting to R semantics: