lmtpd: Trying to unput wrong character

[Mark]

>>> Presumably this is non-standard. Should it be something that Cyrus
>>> handles better, or should be something that Postfix repairs or rejects?
>>
>
> Should this one work?
>
> http://www.postfix.org/postconf.5.html#message_strip_characters

Thanks.  That looks like it should do the job. 

message_strip_characters = \0

I'll try it out (although so far only one message out of hundreds of
thousands has caused trouble).

Mark