We wrote a trigger to email select individuals when an attachment is added to a contract record (see http://boards.developerforce.com/t5/Apex-Code-Development/How-to-Satisfy-quot-test-coverage-quot-for-a-Trigger/m-p/494099/highlight/true#M91277 for the original thread/code).

This worked fine for a while, but now when we add an attachment, mysteriously no system email is being sent.  Nothin in the debug logs to suggest a problem, and the trigger is still active.

Any ideas?

Here's the trigger code:
trigger Send_Email on Attachment (after insert) {
 List<Id> contractIds=new List<Id>();
   for (Attachment att : trigger.new)
   {
      contractIds.add(att.parentId);
   }
   Map<Id, Contract> contracts=new Map<Id, Contract>();
   contracts.putAll([select id, Name, contract.ContractNumber from Contract where id IN :contractIds]);
   Attachment attach = trigger.new[0];
   Messaging.SingleEmailMessage mail = new    Messaging.SingleEmailMessage();
   String[] toAddresses = new String[] {'xxx@xxx.org'};
   String[] bccAddresses = new String[] {'xxx@xxx.com'};
   mail.setToAddresses(toAddresses);
   mail.setbccAddresses(bccAddresses);
   mail.setReplyTo('donotreply@xxx.org');
   mail.setSenderDisplayName('Salesforce Support');
   Contract contract=contracts.get(attach.parentId);
   if (null!=contract)
   {
      mail.setSubject('Attachment Added on : ' + contract.name + ' for ' + contract.ContractNumber);
      mail.setHTMLBody('An attachment has been added to the above Contract record.  Please visit Salesforce for details: https://na5.salesforce.com/' + contract.id);
   Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });
   }
}