sendmail bug can cause loops

[Geoffrey Collyer]

On utcsstat (a V7 system), we occasionally found sendmails looping,
apparently parsing mail addresses.  This was caused by the system 3
DQS-11 RJE subsystem handing to sendmail as an address a garbled
argument, containing characters with their 0200 bits set, produced by
dereferencing a null pointer (RJE has been fixed).

I think sendmail can be fixed to prevent such loops by finding every
reference to a <ctype.h> macro and prepending a check for isascii(c).
I have not done so yet since fixing RJE has stopped the loops, but I
intend to.

Geoff Collyer, U. of Toronto