$ wget ftp://ftp.fu-berlin.de/pub/unix/news/slrn/slrn-0.9.8.0.tar.bz2
$ bzip2 -d slrn-0.9.8.0.tar.bz2
$ cd slrn-0.9.8.0/src
$ patch -p1 < /path/to/slrn-0.9.8.0-useragent-patch
$ ./configure && make && make install
At least, just add ``set useragent "any useragent"´´ to your ~/.slrnrc

diff slrn-0.9.8.0-orig/src/post.c.orig slrn-0.9.8.0/src/post.c
--- slrn-0.9.8.0-orig/src/post	Thu Jul 31 19:21:18 2003
+++ slrn-0.9.8.0/src/post.c	Sat Dec 20 11:55:34 2003
@@ -79,6 +79,7 @@
 char *Slrn_Save_Posts_File;
 char *Slrn_Save_Replies_File;
 char *Slrn_Signoff_String;
+char *Slrn_Custom_User_Agent;
 
 int Slrn_Generate_Date_Header = 0;
 int Slrn_Generate_Message_Id = 1;
@@ -1428,8 +1429,11 @@
 		      slrn_mime_add_headers (fcc_fp);
 		    }
 #endif
-		  post_printf (fcc_fp, "User-Agent: slrn/%s (%s)\n\n",
-					    Slrn_Version, system_os_name);
+		  if ((NULL != Slrn_Custom_User_Agent) && (*Slrn_Custom_User_Agent != 0)) {
+			  post_printf (fcc_fp, "User-Agent: %s \n\n", Slrn_Custom_User_Agent);
+		  } else {
+			  post_printf (fcc_fp, "User-Agent: slrn/%s (%s)\n\n", Slrn_Version, system_os_name);
+		  }
 		  header = 0;
 #if SLRN_HAS_MIME
 		  if (Slrn_Use_Mime & MIME_DISPLAY) fp = slrn_mime_encode (fp);
diff slrn-0.9.8.0-orig/src/post.h.orig slrn-0.9.8.0/src/post.h
--- slrn-0.9.8.0-orig/src/post.h	Thu Jul 31 18:15:36 2003
+++ slrn-0.9.8.0/src/post.h	Sat Dec 20 11:55:49 2003
@@ -37,3 +37,4 @@
 extern char *Slrn_Signoff_String;
 extern int Slrn_Netiquette_Warnings;
 extern int Slrn_Use_Recom_Id;
+extern char *Slrn_Custom_User_Agent;
diff slrn-0.9.8.0-orig/src/startup.c.orig slrn-0.9.8.0/src/startup.c
--- slrn-0.9.8.0-orig/src/startup.c	Mon Aug 25 17:01:17 2003
+++ slrn-0.9.8.0/src/startup.c	Sat Dec 20 11:56:26 2003
@@ -608,6 +608,7 @@
 
 Slrn_Str_Var_Type Slrn_Str_Variables [] = /*{{{*/
 {
+     {"useragent", &Slrn_Custom_User_Agent},
      {"failed_posts_file", &Slrn_Failed_Post_Filename},
 #if ! SLRN_HAS_STRICT_FROM
      {"hostname", &Slrn_User_Info.hostname},