When I tried to remind all students who did not yet fill in the questionnaire, I got a Gateway time-out.
The bad thing about this is that the process stopped somewhere in the middle. From that point on I could not see which students were sent a reminder and which students were not sent a reminder.
I talked to my server administrator about this and he said it would be better if 'The handling of sending e-mail should be asynchronous.'.
I don't know what this means in computer-terms, but I think it means something like 'even when the process receives a time-out, still all the emails should be send'.
Is this something people can understand?
FYI: the number of students being reminded about the questionnaire was around 4000. I think the time-out is from apache and is set to 5 minutes.