I noticed the following limitation when using GmailApp in Google Apps Script:
var threads = GmailApp.search("to:[email protected]");
Logger.log(threads.length); // 250 max
var threads = GmailApp.search("label:mylabel");
Logger.log(threads.length); // 500 max
var label = GmailApp.getUserLabelByName('mylabel');
var threads2 = label.getThreads();
Logger.log(threads2.length); // 500 max
How would you make a job (such as extracting email adresses and adding them to a list) on more than 500 or 250 threads?
Would you do it manually by splitting by dates (not very beautiful but probably working)?