rename Action to Handling. Thanks to rgmnetid for the suggestion.

mail/base/content/junkMail.xul

@@ -136,7 +136,7 @@
       </groupbox>           
                     
         <groupbox flex="1">
-          <caption class="tab-caption" label="Action"/>            
+          <caption class="tab-caption" label="&handling.label;"/>            
             <vbox align="start">
                 <checkbox id="moveOnSpam" oncommand="conditionallyEnableUI('moveOnSpam')" label="&move.label;"/>
                 <radiogroup id="moveTargetMode">
@@ -185,7 +185,7 @@
         </groupbox>
 
         <groupbox>
-          <caption class="tab-caption" label="Logging"/>
+          <caption class="tab-caption" label="&log.label;"/>
           <hbox>
             <description>&loggingDescription.label;</description>      
             <spacer flex="1"/>

mail/base/locale/junkMail.dtd

@@ -20,6 +20,8 @@
 <!ENTITY manualMarkModeMove.label "Move them to the &quot;Junk&quot; folder">
 <!ENTITY manualMarkModeDelete.label "Delete them">
 <!ENTITY renderWithSafeHtml.label "When displaying HTML messages marked as junk, sanitize the HTML">
+<!ENTITY log.label "Logging">
+<!ENTITY handling.label "Handling">
 
 <!ENTITY account.label "Account:">
 <!ENTITY account.accesskey "A">