{!REQUIRESCRIPT ("/soap/ajax/13.0/connection.js")}
var records ={!GETRECORDIDS($ObjectType.Contact)};
var newRecords = [];
var today = new Date();

if (records[0] == null) {
  alert("Sélectionnez au moins un Contact")
}
else {

  for (var n=0; n<records.length; n++) {
   var c = new sforce.SObject("Contact");
   c.id = records[n];
   c.E_mail_proposition_intervention__c = true;
   c.Date_envoi_e_mail_proposition_interventi__c = today;
   newRecords.push(c);
  }

result = sforce.connection.update(newRecords);
window.location.reload();
alert("E-mails envoyés");
}`