The most important factor is researching Informatics. Every level of Informatics increases the chance of success and the level of detail that will be provided on a successful scouting attempt. To successfully scout an area or a city your Informatics level must be equal to or higher than the area being scouted.
The number of scouts sent on a scouting expedition also contributes to the success of the mission. For every level of the area being scouted a minimum of 10 scouts should be sent.
You can include a hero in your scouting mission. This will increase the level of detailed information. The higher intelligence of the hero, the more he affects the outcome. Just remember, If scouts are detected and killed, the hero may be as well!

start sending ievony codes to each persons main cities mail box why would you guys post just a few codes for thousands of ppl to look at only few can have
because it’s not our job to decide who gets them.
how do I prevent my city from being scouted?
just send 100 scouts with lv10 informatics with a hero with 500 intelegence and you will get the right report. if it is far just send out 1 transpoter with lv 10 logistitcs and you will be good.