Ouch! Just got a call from a client wondering that he hadn’t got any emails for a few days and if I could look into the matter. And sure enough: his server side filter was set to sort out any email with a recipient numerically greater than 7! Which, apparently, was true for every email he received. What had happened? Upgrading to avelsieve-1.9.4 had introduced a bug that would set the header to the default value (To:) when saving changes to a rule. So after modifying any rule that used, say, the X-Spam-Score: header would then use the “To:”-header instead upon saving (and spew out an error message Warning: Cannot modify header information - headers already sent.)

Having not noticed either of that, his filter now happily shoved everything into quarantine... (Where they luckily were easily retrieved)

The solution (found here)? Remove the print_r($c); statement in line 53 of the avelsieve/include/process_user_input.inc.php.

Note to myself: more testing!!