Get single emails sent / Single email limit number to create alert when approaching the limit

Question

My organization sends emails via Apex single email in some cases, We are sending the mails to users whenever possible, but sometimes we need to send to external mail, that's causing us to use the 1000 single email limit. Recently We are having issues of passing this limit which causes email not to be sent, or code to fail.

Except from the workbench, Is is possible to get the remaining single emails limit we've left?

The idea is to create an alert whenever the limit is approaching its limit, Any Other ideas will also be great

Answer 1

Yes, you can use the System.Limits class from Apex. Here is a link to the System Limits documentation.

//This is how many email calls have been made
System.debug(System.limits.getEmailInvocations());
//This is how many in total are allowed  
System.debug(System.limits.getLimitEmailInvocations());

Your code can look at these two numbers to work out if you are getting close to the threshold and to act accordingly.

Answer 2

Another pattern you can use is the following

try {
    Messaging.reserveSingleEmailCapacity(count);
    ... send email(s)
}
catch (System.HandledException) {
    .. alert user and say try again next day ...or
    .. alert sysad and use an async pattern to queue for next day to retry
}