Recently migrated to PB2019 R2 Build 2328 and Outlook 365/Win10

coming across a weird issue with my application exe. works fine in the code. we have a screen in the application to send email on a button click. it creates a local mailsession object and after sending email it destroys the mail session object. This works fine in PB code. I can click 'Send' button any number of times and emails goes through that many times.

But after I build the code, and get a 32-bit exe, I am able to send email only for first time. from second time, I get a success return code from 'mailSend', but email is not sent - it is not in outlook nor sent items. 

code is as below:

lms_session = create mailSession
if lms_session.mailLogon() <> mailReturnSuccess! then
 messageBox("Mail Out", "Unable to connect to e-mail server.")
 return FAILURE
end if

lmr_return = lms_session.mailSend(imm_message)

-----all return codes validated and appropriate message is displayed.

if isValid(lms_session) then

 lms_session.mailLogoff()
 destroy lms_session
end if

Has anyone come across this issue. Am I building exe wrong? Issue occurs even on the PC where PB2019 is installed and on client machines.