diff --git a/src/engine/imap/api/imap-account.vala b/src/engine/imap/api/imap-account.vala
index 9f44172e..16969d10 100644
--- a/src/engine/imap/api/imap-account.vala
+++ b/src/engine/imap/api/imap-account.vala
@@ -4,7 +4,7 @@
  * (version 2.1 or later).  See the COPYING file in this distribution. 
  */
 
-public class Geary.Imap.Account : Geary.AbstractAccount, Geary.RemoteAccount {
+private class Geary.Imap.Account : Geary.AbstractAccount, Geary.RemoteAccount {
     // all references to Inbox are converted to this string, purely for sanity sake when dealing
     // with Inbox's case issues
     public const string INBOX_NAME = "INBOX";
@@ -28,22 +28,6 @@ public class Geary.Imap.Account : Geary.AbstractAccount, Geary.RemoteAccount {
         return Geary.Email.Field.HEADER | Geary.Email.Field.BODY;
     }
     
-    public async string? get_folder_delimiter_async(string toplevel,
-        Cancellable? cancellable = null) throws Error {
-        if (delims.has_key(toplevel))
-            return delims.get(toplevel);
-        
-        MailboxInformation? mbox = yield session_mgr.fetch_async(toplevel, cancellable);
-        if (mbox == null) {
-            throw new EngineError.NOT_FOUND("Toplevel folder %s not found on %s", toplevel,
-                session_mgr.to_string());
-        }
-        
-        delims.set(toplevel, mbox.delim);
-        
-        return mbox.delim;
-    }
-    
     public override async Gee.Collection<Geary.Folder> list_folders_async(Geary.FolderPath? parent,
         Cancellable? cancellable = null) throws Error {
         Geary.FolderPath? processed = process_path(parent, null,
diff --git a/src/engine/imap/api/imap-email-identifier.vala b/src/engine/imap/api/imap-email-identifier.vala
index 2baa8600..949a689a 100644
--- a/src/engine/imap/api/imap-email-identifier.vala
+++ b/src/engine/imap/api/imap-email-identifier.vala
@@ -4,7 +4,7 @@
  * (version 2.1 or later).  See the COPYING file in this distribution. 
  */
 
-public class Geary.Imap.EmailIdentifier : Geary.EmailIdentifier {
+private class Geary.Imap.EmailIdentifier : Geary.EmailIdentifier {
     public Imap.UID uid { get; private set; }
     
     public EmailIdentifier(Imap.UID uid) {
diff --git a/src/engine/imap/api/imap-folder-extensions.vala b/src/engine/imap/api/imap-folder-extensions.vala
index dc0e33ab..8e09ae0a 100644
--- a/src/engine/imap/api/imap-folder-extensions.vala
+++ b/src/engine/imap/api/imap-folder-extensions.vala
@@ -4,7 +4,7 @@
  * (version 2.1 or later).  See the COPYING file in this distribution. 
  */
 
-public interface Geary.Imap.FolderExtensions : Geary.Folder {
+private interface Geary.Imap.FolderExtensions : Geary.Folder {
     /**
      * Much like Geary.Folder.list_email_async(), but this list operation allows for a range of
      * emails to be specified by their UID rather than position (message number).  If low is null
diff --git a/src/engine/imap/api/imap-folder.vala b/src/engine/imap/api/imap-folder.vala
index a7e43062..64198a4b 100644
--- a/src/engine/imap/api/imap-folder.vala
+++ b/src/engine/imap/api/imap-folder.vala
@@ -4,7 +4,7 @@
  * (version 2.1 or later).  See the COPYING file in this distribution. 
  */
 
-public class Geary.Imap.Folder : Geary.AbstractFolder, Geary.RemoteFolder, Geary.Imap.FolderExtensions {
+private class Geary.Imap.Folder : Geary.AbstractFolder, Geary.RemoteFolder, Geary.Imap.FolderExtensions {
     public const bool CASE_SENSITIVE = true;
     
     private ClientSessionManager session_mgr;
@@ -31,10 +31,6 @@ public class Geary.Imap.Folder : Geary.AbstractFolder, Geary.RemoteFolder, Geary
         return path;
     }
     
-    public Trillian is_readonly() {
-        return readonly;
-    }
-    
     public override Geary.FolderProperties? get_properties() {
         return properties;
     }
diff --git a/src/engine/api/geary-abstract-account.vala b/src/engine/impl/geary-abstract-account.vala
similarity index 100%
rename from src/engine/api/geary-abstract-account.vala
rename to src/engine/impl/geary-abstract-account.vala
diff --git a/src/engine/api/geary-abstract-folder.vala b/src/engine/impl/geary-abstract-folder.vala
similarity index 100%
rename from src/engine/api/geary-abstract-folder.vala
rename to src/engine/impl/geary-abstract-folder.vala
diff --git a/src/engine/api/geary-engine-account.vala b/src/engine/impl/geary-engine-account.vala
similarity index 100%
rename from src/engine/api/geary-engine-account.vala
rename to src/engine/impl/geary-engine-account.vala
diff --git a/src/engine/api/geary-engine-folder.vala b/src/engine/impl/geary-engine-folder.vala
similarity index 100%
rename from src/engine/api/geary-engine-folder.vala
rename to src/engine/impl/geary-engine-folder.vala
diff --git a/src/engine/api/geary-generic-imap-account.vala b/src/engine/impl/geary-generic-imap-account.vala
similarity index 100%
rename from src/engine/api/geary-generic-imap-account.vala
rename to src/engine/impl/geary-generic-imap-account.vala
diff --git a/src/engine/api/geary-generic-imap-folder.vala b/src/engine/impl/geary-generic-imap-folder.vala
similarity index 100%
rename from src/engine/api/geary-generic-imap-folder.vala
rename to src/engine/impl/geary-generic-imap-folder.vala
diff --git a/src/engine/api/geary-gmail-account.vala b/src/engine/impl/geary-gmail-account.vala
similarity index 100%
rename from src/engine/api/geary-gmail-account.vala
rename to src/engine/impl/geary-gmail-account.vala
diff --git a/src/engine/api/geary-local-interfaces.vala b/src/engine/impl/geary-local-interfaces.vala
similarity index 96%
rename from src/engine/api/geary-local-interfaces.vala
rename to src/engine/impl/geary-local-interfaces.vala
index fe81ab81..b9d956a3 100644
--- a/src/engine/api/geary-local-interfaces.vala
+++ b/src/engine/impl/geary-local-interfaces.vala
@@ -4,7 +4,7 @@
  * (version 2.1 or later).  See the COPYING file in this distribution. 
  */
 
-public interface Geary.LocalAccount : Object, Geary.Account {
+private interface Geary.LocalAccount : Object, Geary.Account {
     public abstract async void clone_folder_async(Geary.Folder folder, Cancellable? cancellable = null)
         throws Error;
     
@@ -23,7 +23,7 @@ public interface Geary.LocalAccount : Object, Geary.Account {
         out int count, Cancellable? cancellable = null) throws Error;
 }
 
-public interface Geary.LocalFolder : Object, Geary.Folder {
+private interface Geary.LocalFolder : Object, Geary.Folder {
     public async abstract bool is_email_present_async(Geary.EmailIdentifier id,
         out Geary.Email.Field available_fields, Cancellable? cancellable = null) throws Error;
      
diff --git a/src/engine/api/geary-remote-interfaces.vala b/src/engine/impl/geary-remote-interfaces.vala
similarity index 68%
rename from src/engine/api/geary-remote-interfaces.vala
rename to src/engine/impl/geary-remote-interfaces.vala
index cc8d35c8..eaa7aacf 100644
--- a/src/engine/api/geary-remote-interfaces.vala
+++ b/src/engine/impl/geary-remote-interfaces.vala
@@ -4,10 +4,7 @@
  * (version 2.1 or later).  See the COPYING file in this distribution. 
  */
 
-public interface Geary.RemoteAccount : Object, Geary.Account {
-    public abstract async string? get_folder_delimiter_async(string toplevel,
-        Cancellable? cancellable = null) throws Error;
-    
+private interface Geary.RemoteAccount : Object, Geary.Account {
     /**
      * Delivers a formatted message with this Account being the sender of record.
      *
@@ -18,6 +15,6 @@ public interface Geary.RemoteAccount : Object, Geary.Account {
         throws Error;
 }
 
-public interface Geary.RemoteFolder : Object, Geary.Folder {
+private interface Geary.RemoteFolder : Object, Geary.Folder {
 }
 
diff --git a/src/engine/api/geary-replay-queue.vala b/src/engine/impl/geary-replay-queue.vala
similarity index 100%
rename from src/engine/api/geary-replay-queue.vala
rename to src/engine/impl/geary-replay-queue.vala
diff --git a/src/engine/sqlite/api/sqlite-account.vala b/src/engine/sqlite/api/sqlite-account.vala
index 7b2033de..b7ae6c06 100644
--- a/src/engine/sqlite/api/sqlite-account.vala
+++ b/src/engine/sqlite/api/sqlite-account.vala
@@ -4,7 +4,7 @@
  * (version 2.1 or later).  See the COPYING file in this distribution. 
  */
 
-public class Geary.Sqlite.Account : Geary.AbstractAccount, Geary.LocalAccount {
+private class Geary.Sqlite.Account : Geary.AbstractAccount, Geary.LocalAccount {
     private class FolderReference : Geary.SmartReference {
         public Geary.FolderPath path;
         
diff --git a/src/engine/sqlite/api/sqlite-folder.vala b/src/engine/sqlite/api/sqlite-folder.vala
index 5aaf7dac..13ca4749 100644
--- a/src/engine/sqlite/api/sqlite-folder.vala
+++ b/src/engine/sqlite/api/sqlite-folder.vala
@@ -7,7 +7,7 @@
 // TODO: This class currently deals with generic email storage as well as IMAP-specific issues; in
 // the future, to support other email services, will need to break this up.
 
-public class Geary.Sqlite.Folder : Geary.AbstractFolder, Geary.LocalFolder, Geary.Imap.FolderExtensions,
+private class Geary.Sqlite.Folder : Geary.AbstractFolder, Geary.LocalFolder, Geary.Imap.FolderExtensions,
     Geary.ReferenceSemantics {
     protected int manual_ref_count { get; protected set; }
     
diff --git a/src/wscript b/src/wscript
index 646f2982..ce1344d1 100644
--- a/src/wscript
+++ b/src/wscript
@@ -14,8 +14,6 @@ def build(bld):
 	bld.common_packages = ['glib-2.0', 'posix' ]
 	
 	bld.engine_src = [
-	'../engine/api/geary-abstract-account.vala',
-	'../engine/api/geary-abstract-folder.vala',
 	'../engine/api/geary-account.vala',
 	'../engine/api/geary-composed-email.vala',
 	'../engine/api/geary-credentials.vala',
@@ -24,20 +22,12 @@ def build(bld):
 	'../engine/api/geary-email-properties.vala',
 	'../engine/api/geary-email.vala',
 	'../engine/api/geary-endpoint.vala',
-	'../engine/api/geary-engine-account.vala',
 	'../engine/api/geary-engine-error.vala',
-	'../engine/api/geary-engine-folder.vala',
 	'../engine/api/geary-engine.vala',
 	'../engine/api/geary-folder-path.vala',
 	'../engine/api/geary-folder-properties.vala',
 	'../engine/api/geary-folder.vala',
-	'../engine/api/geary-generic-imap-account.vala',
-	'../engine/api/geary-generic-imap-folder.vala',
-	'../engine/api/geary-gmail-account.vala',
-	'../engine/api/geary-local-interfaces.vala',
 	'../engine/api/geary-personality.vala',
-	'../engine/api/geary-remote-interfaces.vala',
-	'../engine/api/geary-replay-queue.vala',
 	'../engine/api/geary-special-folder.vala',
 	
 	'../engine/common/common-message-data.vala',
@@ -84,6 +74,17 @@ def build(bld):
 	'../engine/imap/transport/imap-serializable.vala',
 	'../engine/imap/transport/imap-serializer.vala',
 	
+	'../engine/impl/geary-abstract-account.vala',
+	'../engine/impl/geary-abstract-folder.vala',
+	'../engine/impl/geary-engine-account.vala',
+	'../engine/impl/geary-engine-folder.vala',
+	'../engine/impl/geary-generic-imap-account.vala',
+	'../engine/impl/geary-generic-imap-folder.vala',
+	'../engine/impl/geary-gmail-account.vala',
+	'../engine/impl/geary-local-interfaces.vala',
+	'../engine/impl/geary-remote-interfaces.vala',
+	'../engine/impl/geary-replay-queue.vala',
+	
 	'../engine/nonblocking/nonblocking-mailbox.vala',
 	'../engine/nonblocking/nonblocking-mutex.vala',
 	'../engine/nonblocking/nonblocking-abstract-semaphore.vala',