In reality despite ConsumeIMAP is stateless, the IMAP server holds /Recent flag that is system read-only flag (theoretically within IMAP session, but how Gmail detect unique session is a BlackBox and I was not able to manage it with NiFi ConsumeIMAP client).   If you want to re-fetch all your historical emails I recommend using ConsumePOP3 NiFi component, with the following setting on Gmail server: Gmail - settings - all - forwarding - Enable POP for all mail After performing such historical fetch you can disable ConsumePOP3 and continue to work with ConsumeIMAP to consume new messages. ... View more

Yes this really helped as the problem was a misconfiguration. The truststore and keystore in Nifi Registry were both pointing to the truststore. On correcting this all is working fine.   Thanks   John ... View more