Milter-greylist

John Villalovos wrote:
 > Jun  3 08:39:47 john-desktop milter-greylist: unexpected void
 > backreference no 1 in regex /.*@\(.*\.\)*example\.com/ against
 > "<example@...>"

I'm afraid I can't explain the message.  But FWIW, I use
a slightly different regex for that kind of things:

/.*[@.]example\.com/

Its purpose is the same:  It matches someone@...
as well as someone@..., but it does not
match someone@....

This regex is more efficient, because grouping with \(\)
combined with "*", "+" or "?" is less efficient than using
character sets with "[]" like above (at least in the regex
library I'm familiar with).  It's also less dependent on
the regex implementation and dialect; it works with basic
REs as well as with extended REs.

Best regards
   Oliver

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