Transactional messages (email etc) can be accessed via the messaging endpoint. The IMAP protocol is supported.
IMAP being the more modern, with a number of functional advantages over the older POP protocol – two significant ones being simultaneous access and folder support.
Use the /rpc/setup?method=SETUP_MESSAGING_ACCOUNT_MANAGE to set up an account use &sslport= or &port= to specify for you want to access the emails – eg use &sslport=993 to access Gmail email accounts with &server=imap.gmail.com.
Use the /rpc/messaging/?method=MESSAGING_EMAIL_ACCOUNT_SEARCH and &getfolders=1 to get a list of available folders and index.
Then using MESSAGING_EMAIL_SEARCH and &folder=[index] to get the messages (folder items) for each folder.
You can also use the &search= function to send IMAP filter requests.
Search Commands List (txt) eg &search=NEW
Setup Gmail Business Email Account