Last night I forwarded an email I'd received to toodledo so that I could action it later. I got a reply, this is most unusual, I don't normally get a reply. On closer investigation it was an error message telling me that my mail couldn't be delivered and giving me just enough of a diagnostic message to be potentially useful.
Thanks for reporting this bug. We were seeing some errors but we hadn't been able to locate the source yet. You helped us find it. It is fixed now.
That really made me feel that raising the issue was helpful, and useful, and that I'd contributed to the fix.