diff --git a/internal_packages/preferences/lib/tabs/preferences-mail-rules.jsx b/internal_packages/preferences/lib/tabs/preferences-mail-rules.jsx
index 1ad825cd1..1b5afebe4 100644
--- a/internal_packages/preferences/lib/tabs/preferences-mail-rules.jsx
+++ b/internal_packages/preferences/lib/tabs/preferences-mail-rules.jsx
@@ -260,6 +260,10 @@ class PreferencesMailRules extends React.Component {
   }
 
   render() {
+    const processDisabled = _.any(this.state.tasks, (task) => {
+      return (task.accountId === this.state.currentAccount.id);
+    });
+
     return (
       <div className="container-mail-rules">
         <section>
@@ -273,8 +277,8 @@ class PreferencesMailRules extends React.Component {
 
           <Flexbox style={{marginTop: 40, maxWidth: 600}}>
             <div>
-              <button className="btn" style={{float: 'right'}} onClick={this._onReprocessRules}>
-                Process all mail
+              <button disabled={processDisabled} className="btn" style={{float: 'right'}} onClick={this._onReprocessRules}>
+                Process entire inbox
               </button>
             </div>
             {this._renderTasks()}
@@ -282,7 +286,7 @@ class PreferencesMailRules extends React.Component {
 
           <p style={{marginTop: 10}}>
             By default, mail rules are only applied to new mail as it arrives.
-            Applying rules to your entire mailbox may take a long time and
+            Applying rules to your entire inbox may take a long time and
             degrade performance.
           </p>
         </section>
diff --git a/src/flux/attributes/attribute-datetime.coffee b/src/flux/attributes/attribute-datetime.coffee
index 625930aa8..5fec13e9e 100644
--- a/src/flux/attributes/attribute-datetime.coffee
+++ b/src/flux/attributes/attribute-datetime.coffee
@@ -32,5 +32,17 @@ class AttributeDateTime extends Attribute
     throw (new Error "AttributeDateTime::lessThan (#{@modelKey}) - this field cannot be queried against") unless @queryable
     new Matcher(@, '<', val)
 
+  # Public: Returns a {Matcher} for objects greater than the provided value.
+  greaterThanOrEqualTo: (val) ->
+    throw (new Error "AttributeNumber::greaterThanOrEqualTo (#{@modelKey}) - you must provide a value") unless val?
+    throw (new Error "AttributeNumber::greaterThanOrEqualTo (#{@modelKey}) - this field cannot be queried against") unless @queryable
+    new Matcher(@, '>=', val)
+
+  # Public: Returns a {Matcher} for objects less than the provided value.
+  lessThanOrEqualTo: (val) ->
+    throw (new Error "AttributeNumber::lessThanOrEqualTo (#{@modelKey}) - you must provide a value") unless val?
+    throw (new Error "AttributeNumber::lessThanOrEqualTo (#{@modelKey}) - this field cannot be queried against") unless @queryable
+    new Matcher(@, '<=', val)
+
 
 module.exports = AttributeDateTime
diff --git a/src/flux/attributes/matcher.coffee b/src/flux/attributes/matcher.coffee
index 5a48525fc..f896abbcf 100644
--- a/src/flux/attributes/matcher.coffee
+++ b/src/flux/attributes/matcher.coffee
@@ -103,6 +103,8 @@ class Matcher
       escaped = 1
     else if val is false
       escaped = 0
+    else if val instanceof Date
+      escaped = val.getTime() / 1000
     else if val instanceof Array
       escapedVals = []
       for v in val
diff --git a/src/flux/tasks/reprocess-mail-rules-task.es6 b/src/flux/tasks/reprocess-mail-rules-task.es6
index ff04800a4..25b10db62 100644
--- a/src/flux/tasks/reprocess-mail-rules-task.es6
+++ b/src/flux/tasks/reprocess-mail-rules-task.es6
@@ -3,6 +3,7 @@ import Task from './task';
 import Thread from '../models/thread';
 import Message from '../models/message';
 import DatabaseStore from '../stores/database-store';
+import CategoryStore from '../stores/category-store';
 import MailRulesProcessor from '../../mail-rules-processor';
 import async from 'async';
 
@@ -12,6 +13,7 @@ export default class ReprocessMailRulesTask extends Task {
     this.accountId = accountId;
     this._processed = this._processed || 0;
     this._offset = this._offset || 0;
+    this._lastTimestamp = this._lastTimestamp || null;
     this._finished = false;
   }
 
@@ -36,14 +38,26 @@ export default class ReprocessMailRulesTask extends Task {
   }
 
   _processSomeMessages = (callback) => {
+    const inboxCategory = CategoryStore.getStandardCategory(this.accountId, 'inbox');
+    if (!inboxCategory) {
+      return callback(new Error("ReprocessMailRulesTask: No inbox category found."));
+    }
+
     // Fetching threads first, and then getting their messages allows us to use
     // The same indexes as the thread list / message list in the app
+
+    // Note that we look for "50 after X" rather than "offset 150", because
+    // running mail rules can move things out of the inbox!
     const query = DatabaseStore
       .findAll(Thread, {accountId: this.accountId})
+      .where(Thread.attributes.categories.contains(inboxCategory.id))
       .order(Thread.attributes.lastMessageReceivedTimestamp.descending())
-      .offset(this._offset)
       .limit(50)
 
+    if (this._lastTimestamp !== null) {
+      query.where(Thread.attributes.lastMessageReceivedTimestamp.lessThan(this._lastTimestamp))
+    }
+
     return query.then((threads) => {
       if (threads.length === 0) {
         this._finished = true;
@@ -61,6 +75,7 @@ export default class ReprocessMailRulesTask extends Task {
         return MailRulesProcessor.processMessages(messages).finally(() => {
           this._processed += messages.length;
           this._offset += threads.length;
+          this._lastTimestamp = threads.pop().lastMessageReceivedTimestamp;
         });
       });
     })