When one of the emails in a queue receives an empty ‘to’ address, the email task will fail on a NPE while sending emails. Consequently, the emails in the queue before the empty-to-email will be send, the others will not, but none will be marked as sent. The next time the email task runs this will happen all over again. Causing about two emails per item in the queue per minute (i.e. SPAM ;) ).

This behavior caused the researchr queue to lockup for a while (and two persons to receive a lot of emails).

Submitted by Sander Vermolen on 6 April 2011 at 10:05

Additionally, I suppose adding emails to the queue also fails when there is an email with an empty target address present. Since, we (except for Lennart and someone registering) have not received any emails from researchr in about a week and there are practically none in the queue.

More robust email sending implemented in r4579: one at a time, if any exception occurs retry sending that email in 3 hours.