#! perl -w
use strict;

while( <DATA> ) {
    s!([%&_~{}^#\\])!\\$1!g;
    print;
}

__DATA__
"% & _ ~ { } ^ # \ "
"Sonntag, 26.05.2013 - 13:13:27","0","Lieber Herr % , & text text with some %special characters"
"Sonntag, 26.05.2013 - 13:35:47","1","Sehr gerne! ^ _~}# and here some other characters"
"Sonntag, 26.05.2013 - 13:49:15","0",":-))"
"Mittwoch, 05.06.2013 - 18:12:09","0","Besten Dank, & hat prima geklappt. {Greetings!}"
"Mittwoch, 05.06.2013 - 19:16:47","1","% _ text text!"
"Mittwoch, 05.06.2013 - 19:17:30","0","~Prima! #Danke!!"
"Samstag, 08.06.2013 - 09:21:09","1","_ 10. Jul Text text %"
"Samstag, 08.06.2013 - 10:08:45","0","Ja, osaka ffm lh 741 & ffm muc lh 114 abflug 16:00"