I've solved it! I added some debug-output that mysteriously solved the crashing of the exporter, but now I've figured out why it got "solved":
write("From: ("+utf8_to_string(from)+") "); //Saves Pike from crashing?!? //Yes, because it crashes this Pike-program when getting ISO-ö obviously!
Since Sat May 17 18:51:11 CEST 2008 Neither Henrik Grubbströms nor Johan Sundström's messages have gotten into the archive. It's obviously because the "ö" in their usernames.
Now it should work though, if the 7.6.112-Pike doesn't have the _mystring[3]='f' => crashes Pike sometimes bug. If this comes through with my åäö-parenthesis, then it works.