David - thanks so much for spending so much effort on this. Appreciate yor help!
I followed all your instructions, but unfortunately, I still have the same problem.
Not knowing php, I digged a little bit deeper into "postie-functions.php" and added printouts at severl places. What I found is that the problem seems to be with the function "imagecreatefromgif" not being found. "postie-functions.php" has a function named "HasFunctions(...)". This function returns "false" when checking for 'imagecreatefromgif'. For all other functions, it seems to check OK. This is weird, don't know what happens here.
When I remove the check for 'imagecreatefromgif', the script continues, the thumbnail generation is invoced, but some other problems occur I'm looking in now.
Any idea why the test for function 'imagecreatefromgif' fails? I'm running this in server 82, which seems to have GD installed. Thanks!