I would expect a mature email client to properly respond to it's own configurable settings.
The configurable settings work just fine when attempting to send email via Outlook using OOM as opposed to the generic "default" email client approach (which would have been the case with GroupWise). Decided to humor myself and spent a few
minutes to get reacquainted with Access using Outlook '2013 (have no idea whether this is the same with OL'2010 but suspect it is) and tested both approaches
(1) DoCmd.SendObject does invoke Outlook's security model but
(2) using the Outlook Object Model in code to send email via Outlook does not - works just fine and no security prompt is encountered
FWIW - using "Docmd.SendObject" is <not> the recommended approach when sending email via Outlook. Your choice as to whether you modify your code accordingly or live with the message.
Some sample code can be found here
DoCmd.SendObject Method (Access)
https://msdn.microsoft.com/en-us/library/ff197046.aspx?f=255&MSPPError=-2147217396
*** the above example is incomplete - you'll need to add Outlook to your references and handle the scenario accordingly in terms of whether or not Outlook is running when your Access code is run to use either GetObject(, "Outlook.Application")
- if Outlook is running or CreateObject("Outlook.Application") if it's not.
Also, as a side comment, equally puzzled why you would continue to run Access '2010 for this if it otherwise works in '2013 (unless there are some other factors involved where whatever has been developed doesn't run in '2013). However that has nothing to
do with the issue at hand.