Hi,
Expensive option now it seems & quite complex but I have software from
https://www.chilkatsoft.com/.
There may be others with similar ActiveX.
I am an OK programmer, certainly no expert by a long shot, just copy others & examples.
I have it pretty much running a full email program, I do not think there is anything is can't so. Downloads direct from my email server. ignores thunderbird but of course emails are there also.
I use .Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate")
CDO for sending as simple & easy but think Chilkat can do also.
Again I think you can cc so will be on iMap sent & think thunderbird
Can handle attachments but prefer not to use & one thing that seemed more tricky.
They seem to be selling but I got the impression not really supported but I might be wrong. Says $289 but sure I would not have paid anything like that but in UK & £100 rings a bell (long time ago) I think I have just licenced Chilkatemail & Chilkatemail2 for iMap email this now seems for everything
It looks like there is still a free trial.
Looks complicated but actually copying example VB6 code can get the basics very easily
It worked for me on previous version of office and now on O365 all good still.
What can be fiddly is really need to use rft and works fine but access html is a little different but again can do all you need. can use plain text but I do like the formatting.