Using SPForm in multiple contexts

I have 4 contexts in one of my MODX Clouds. SPForm and QuickEmail work with the default context, but not the others, but only if I use SMTP and configure it in both System Settings and SPForm Property Set.

So I added the various mail_smtp_settings to override System Settings. It doesn't work: SPForm functions correctly, but the email is never sent. QuickEmail generates a simple "Unauthorized" message.

Note: all SPForms use Property Sets. My call is

I've cleared the cache via Mgr and manually. Nothing works. I of course doublechecked to make sure that I had the System Setting correctly inputted in the Context Settings area and that the password was correct and the username was the full email address, ssl, port#, the whole schmear for what worked in the default settings.

None of the other contexts' SPForm is able to send email. It appears to work correctly and debug yields the appropriate info; email simply isn't sent.