TL wrote:
A.E. Gelat wrote:
R.P. stands for Recette Principale, meaning General or
Head Post Office. It is difficult to read the postmark
and the dark area on the lower left of the envelope.
Could you post an enlarged view and with less exposure?
for some reason, Paint Shop Pro could not accept the
format of the message, although I thought that .jpg was
OK.

Tony,
Here is a 3.2 MB scan:
http://cover.home.mindspring.com/11-28/algiers.jpg
It is fresh from photoshop.
thanks,
TL

I concur with Tony for R.P. ;-)
I would say the bottom part of the cancels ends with an R.
Normally this zone indicates the district (département).
There were three of them in french Algeria:
Alger, Constantine, Oran, named after their main city.

So my best guess, here, is ALGER R.P. / ALGER

--
Best regards,
Bruno