Apex beginner - Email from a trigger

Question

This is the first bit of code I have written using APEX so am learning... know a bit of Java (to a graduate level) but I don't know why this is not working.

I know that it is not giving an error to salesforce as before it was telling me (hence the commented out debug at the end. I change a contacts email and it just does it, but I receive no emails! Here is the code and thank you for any help!

trigger Test1 on Contact (after update) {

//IF Email has changed (look at the old email and compare to new)
if(trigger.old[0].Email != trigger.new[0].Email){


    //Commit current transaction, reserver email capacity
    Messaging.reserveSingleEmailCapacity(1);
    //Create an email message object
    Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();

    //List<Messaging.SendEmailResult> results = new list<Messaging.SendEmailResult>();
    //hold email address
    String[] toAddresses = new String[] {trigger.new[0].Email};

    //Assign new address string
    mail.setToAddresses(toAddresses);
    //specify return ad (assuming as being sent from server)    
    mail.setReplyTo('XXX@example.com');
    //sender name
    mail.setSenderDisplayName('Mr Apex Tester');
    //Subject Specification
    mail.setSubject('Subjected to Learning');
    //And... the content
    mail.setPlainTextBody('You have just changed your SalesForce contact email from ' + trigger.old[0].Email + ' to ' + trigger.new[0].Email + '. If this was not intentional please log back into Salesforce.com and ammend you details.');

    //if (!results.get(0).isSuccess()){                      
        //System.debug('That didnt really work did it? Reason: ' + results.get(0).getErrors()[0].getMessage());
    }
}

Answer 1

the first trouble into your code is that your trigger is not BULK read about it here

bulk trigger #1

bulk trigger #2

the next trouble is that you don't send email with Messaging.sendEmail

try the following:

    trigger Test1 on Contact (after update) {
        Messaging.reserveSingleEmailCapacity(trigger.size);
        List<Messaging.SingleEmailMessage> emails = new List<Messaging.SingleEmailMessage>();
        for (Contact c : trigger.new) { // walk through all records which is processed
            Contact old = trigger.oldMap.get(c.Id); // get old record from oldMap
            if (old.Email != c.Email ) { // check current email 
                Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
                email.setToAddresses(new String[] {c.Email};);
                email.setReplyTo('XXX@example.com');
                email.setSenderDisplayName('Mr Apex Tester');
                email.setSubject('Subjected to Learning');
                email.setPlainTextBody('You have just changed your SalesForce contact email from ' + 
                    old.Email + ' to ' + c.Email +
                     '. If this was not intentional please log back into Salesforce.com and ammend you details.');
                emails.add(email);
            }
        }
        Messaging.sendEmail(emails);
    }