Finally works correct for SMTP too. Closes #24.

Someone please check MySQL script!

README.md

@@ -16,3 +16,6 @@ This plugin allows users to switch between different accounts (including remote)
 * Branch 3.X - for Roundcube v1.3
 
 Please specify verion like "~2.0" in your composer.json file for ident_switch requirement. In this case you will stay inside compatible branch until you manually update ypur Roundcube installation.
+
+### Switching SMTP ###
+Plugin also switched SMTP credentials but only for server specified in general config. You should use %u and %p substitutions for user and password to make it work. This substitutions are replaced by username and password for selected IMAP account.

SQL/mysql.initial.sql

@@ -11,8 +11,7 @@ CREATE TABLE IF NOT EXISTS ident_switch
 		int(10) UNSIGNED
 		NOT NULL,
 	username
-		varchar(64)
-		NOT NULL,
+		varchar(64),
 	password
 		varchar(64),
 	host

SQL/mysql/2018071600.sql

@@ -0,0 +1,6 @@
+ALTER TABLE
+	ident_switch
+MODIFY
+	username
+	varchar(64)
+	NULL;

SQL/postgres.initial.sql

@@ -13,8 +13,7 @@ CREATE TABLE ident_switch
 		REFERENCES identities(identity_id) ON DELETE CASCADE ON UPDATE CASCADE
 		UNIQUE,
 	username
-		varchar(64)
-		NOT NULL,
+		varchar(64),
 	password
 		varchar(64),
 	host

SQL/postgres/2018081600.sql

@@ -0,0 +1,5 @@
+ALTER TABLE
+	ident_switch
+ALTER COLUMN
+	username
+DROP NOT NULL;

ident_switch.php

@@ -150,16 +150,29 @@ class ident_switch extends rcube_plugin
 
 	function on_smtp_connect($args)
 	{
+		$iid = $_SESSION['iid' . self::MY_POSTFIX];
+		if (!is_integer($iid) || $iid == -1)
+			return $args;
+
 		$rc = rcmail::get_instance();
 
-		// TODO: Rewrite with full settings!
-
-		if (strcasecmp($rc->user->data['username'], $_SESSION['username']) !== 0)
+		$sql = 'SELECT host, flags, port, username, password, iid FROM ' . $rc->db->table_name(self::TABLE) . ' WHERE iid = ? AND user_id = ?';
+		$q = $rc->db->query($sql, $iid ,$rc->user->ID);
+		$r = $rc->db->fetch_assoc($q);
+		if (is_array($r))
 		{
-			if ($args['smtp_user'] == '%u')
-				$args['smtp_user'] = $rc->user->data['username'];
-			if ($args['smtp_pass'] == '%p')
-				$args['smtp_pass'] = $rc->decrypt($_SESSION['password' . self::MY_POSTFIX]);
+			if (!$r['username'])
+			{ // Load email from identity
+				$sql = 'SELECT email FROM ' . $rc->db->table_name('identities') . ' WHERE identity_id = ?';
+				$q = $rc->db->query($sql, $r['iid']);
+				$rIid = $rc->db->fetch_assoc($q);
+
+				$r['username'] = $rIid['email'];
+			}
+
+			// Exactly the same in core SMTP handler
+			$args['smtp_user'] = str_replace('%u', $r['username'], $args['smtp_user']);
+			$args['smtp_pass'] = str_replace('%p', $rc->decrypt($r['password']), $args['smtp_pass']);
 		}
 
 		return $args;