Originally Posted by
ISTFlyer
Thanks for reporting back.
Did you mean transfer document check instead of transit immigration? If I'm not wrong there shouldn't be any security or passport check ( by the border police ) when transiting N/S to N/S.
ATH has a passport check when transiting N/S to N/S. It is not immigration but rather a document / ID conformance check.
The system is quite confusing but couple of years ago I called the police in ATH airport to confirm this, as a friend was transiting N/S to N/S without a Schengen Visa and they kindly confirmed that there would be a passport check but no visa required as in the rest of the Schengen Area.