My Node app is using imap module to retrieve emails:
var f = imap.seq.fetch('1:3', {
bodies: ['HEADER.FIELDS (FROM TO SUBJECT DATE)', 'TEXT'],
struct: true
});
The app fetches emails with seqno 1-3 in gmail mail box. However I did not see those 3 emails in the mail box and only found them by searching the email subject. It seems the imap module retrieve some real old emails which are not visible in the mail box. I am wondering how seqno is issued in a mail box and weather a seqno for an email is unique and stay unchanged after issuing.