[CQ-Contest] Band edge --- how do you warn a guy?

[K0HB]

Yesterday evening (Saturday) during SS I noticed K3xxx (callsign
fictitious) blissfully running a nice open freq at 3751.000.  Since he was
running LSB, a fair portion of his signal was down below the band-edge.   
I'm sure it was inadvertent, and there was no way for me to tell him
without running afoul of the band-edge myself.   Unfortunately not only did
he run afoul of a possible letter from Riley, but so did probably 100 other
US stations who worked him (he was a good crisp operator, and remained on
the QRG for over an hour).

I tried to warn him using CW, but couldn't get his attention.  How (short
of moving to Canada, or hunting down his phone number in the heat of the
contest) would you notify someone that they're out of band?  (Or should I
just keep my big nose out of it?)

73, Hans, K0HB

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  I found it!  http://tinyurl.com/upn9