Hi @Locos, trigger nodes (including the IMAP one) can’t use expressions I am afraid. This is because there is no previously node from which they could fetch data.
On the (regular) SMTP node you can, however, use expressions in your credentials that can read details from previous nodes:
So the SMTP part should work already, but for the IMAP part you’d need a regular IMAP node instead of the trigger. This is not something we currently offer, but perhaps you want to open a feature request?
Yep, this also works for the password (just tested to be sure). I didn’t include that in the screenshot though because the expression preview would display that password