diff --git a/mozilla/mailnews/local/src/nsPop3Protocol.cpp b/mozilla/mailnews/local/src/nsPop3Protocol.cpp
index bf574451d61..54c5afb6c00 100644
--- a/mozilla/mailnews/local/src/nsPop3Protocol.cpp
+++ b/mozilla/mailnews/local/src/nsPop3Protocol.cpp
@@ -40,11 +40,14 @@
 #include "nsLocalStringBundle.h"
 #include "nsTextFormater.h"
 #include "nsCOMPtr.h"
+#include "nsIPref.h" 
+
+#define PREF_MAIL_ALLOW_AT_SIGN_IN_USER_NAME "mail.allow_at_sign_in_user_name"
 
 static PRLogModuleInfo *POP3LOGMODULE = nsnull;
 
 static NS_DEFINE_CID(kNetSupportDialogCID, NS_NETSUPPORTDIALOG_CID);
-
+static NS_DEFINE_CID(kPrefServiceCID, NS_PREF_CID); 
 
 /* km
  *
@@ -377,7 +380,8 @@ nsPop3Protocol::nsPop3Protocol(nsIURI* aURL)
 	m_totalDownloadSize(0),
 	m_totalBytesReceived(0),
 	m_lineStreamBuffer(nsnull),
-	m_pop3ConData(nsnull)
+	m_pop3ConData(nsnull),
+	m_allow_at_sign_in_mail_user_name(PR_FALSE)
 {
 	SetLookingForCRLF(MSG_LINEBREAK_LEN == 2);
 }
@@ -425,6 +429,18 @@ nsresult nsPop3Protocol::Initialize(nsIURI * aURL)
   if(!m_lineStreamBuffer)
 	  return NS_ERROR_OUT_OF_MEMORY;
 
+  NS_WITH_SERVICE(nsIPref, prefs, kPrefServiceCID, &rv);
+  if (NS_FAILED(rv)) return rv;
+
+/* the old comment in mkpop3.c in the old source tree:
+ *
+ * Well, someone finally found a legitimate reason to put an @ in the
+ * mail server user name. They're trying to use the user name as a UID
+ * in the LDAP directory, and the UIDs happen to have the format
+ * foo@bar.com. We don't change our default behavior, but we let admins
+ * turn it off if they want
+ */
+  rv = prefs->GetBoolPref(PREF_MAIL_ALLOW_AT_SIGN_IN_USER_NAME, &m_allow_at_sign_in_mail_user_name);
   return rv;
 }
 
@@ -467,9 +483,26 @@ void nsPop3Protocol::UpdateProgressPercent (PRUint32 totalDone, PRUint32 total)
 
 void nsPop3Protocol::SetUsername(const char* name)
 {
-    NS_ASSERTION(name, "no name specified!");
-	if (name)
+	NS_ASSERTION(name, "no name specified!");
+	if (name) {
 		m_username = name;
+		/*
+		 * If we are called with data like "fred@bedrock.com", then we will
+		 * help the user by ignoring the stuff after the "@".  People with
+		 * @ signs in their user names will be hosed.  They also can't possibly
+		 * be current happy internet users.  This will waste a few bytes,
+		 * but was the minimal change to make in order to ship cheddar.
+		 * (it might even save bytes by avoiding the code which does the
+		 * right thing)
+		 */
+		if (!m_allow_at_sign_in_mail_user_name) {
+			PRInt32 atPos = -1;
+			atPos = m_username.FindChar('@');
+			if (atPos != -1) {
+				m_username.Truncate(atPos);
+			}
+		}
+	}
 }
 
 nsresult nsPop3Protocol::GetPassword(char ** aPassword)
diff --git a/mozilla/mailnews/local/src/nsPop3Protocol.h b/mozilla/mailnews/local/src/nsPop3Protocol.h
index 4595e101a97..3da183c2fae 100644
--- a/mozilla/mailnews/local/src/nsPop3Protocol.h
+++ b/mozilla/mailnews/local/src/nsPop3Protocol.h
@@ -288,6 +288,7 @@ private:
 	
 	nsMsgLineStreamBuffer   * m_lineStreamBuffer; // used to efficiently extract lines from the incoming data stream
     Pop3ConData* m_pop3ConData;
+    PRBool m_allow_at_sign_in_mail_user_name;
     void FreeMsgInfo();
 
 	//////////////////////////////////////////////////////////////////////////////////////////