diff --git a/dictionaries/cs.dictionary.itop.ui.php b/dictionaries/cs.dictionary.itop.ui.php
index 5a9651419..7d91469f9 100755
--- a/dictionaries/cs.dictionary.itop.ui.php
+++ b/dictionaries/cs.dictionary.itop.ui.php
@@ -466,6 +466,8 @@ Dict::Add('CS CZ', 'Czech', 'Čeština', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Množství',
 	'UI:GroupBy:Count+' => 'Množství prvků',
 	'UI:CountOfObjects' => 'Počet objektů odpovídajícíh ktritériím: %1$d',
diff --git a/dictionaries/da.dictionary.itop.ui.php b/dictionaries/da.dictionary.itop.ui.php
index aa2c546d5..945a1fa12 100644
--- a/dictionaries/da.dictionary.itop.ui.php
+++ b/dictionaries/da.dictionary.itop.ui.php
@@ -453,6 +453,8 @@ Dict::Add('DA DA', 'Danish', 'Dansk', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Antal',
 	'UI:GroupBy:Count+' => 'Antal af elementer',
 	'UI:CountOfObjects' => '%1$d objekter opfylder kriteriet.',
diff --git a/dictionaries/de.dictionary.itop.ui.php b/dictionaries/de.dictionary.itop.ui.php
index 1ef51b3b5..21193745a 100644
--- a/dictionaries/de.dictionary.itop.ui.php
+++ b/dictionaries/de.dictionary.itop.ui.php
@@ -452,6 +452,8 @@ Dict::Add('DE DE', 'German', 'Deutsch', array(
 	'UI:Error:MaintenanceTitle' => 'Wartung',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Anzahl',
 	'UI:GroupBy:Count+' => 'Anzahl der Elemente',
 	'UI:CountOfObjects' => '%1$d Objekte, die das Kriterium erfüllen.',
diff --git a/dictionaries/en.dictionary.itop.ui.php b/dictionaries/en.dictionary.itop.ui.php
index 18420b2d8..b6ddfcf7f 100644
--- a/dictionaries/en.dictionary.itop.ui.php
+++ b/dictionaries/en.dictionary.itop.ui.php
@@ -468,6 +468,8 @@ Dict::Add('EN US', 'English', 'English', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)',
+
 	'UI:GroupBy:Count' => 'Count',
 	'UI:GroupBy:Count+' => 'Number of elements',
 	'UI:CountOfObjects' => '%1$d objects matching the criteria.',
diff --git a/dictionaries/es_cr.dictionary.itop.ui.php b/dictionaries/es_cr.dictionary.itop.ui.php
index b24fd05fb..c940bb277 100644
--- a/dictionaries/es_cr.dictionary.itop.ui.php
+++ b/dictionaries/es_cr.dictionary.itop.ui.php
@@ -465,6 +465,8 @@ Dict::Add('ES CR', 'Spanish', 'Español, Castellaño', array(
 	'UI:Error:MaintenanceTitle' => 'Mantenimiento',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Cuenta',
 	'UI:GroupBy:Count+' => 'Número de Elementos',
 	'UI:CountOfObjects' => '%1$d Elementos cumplen Criterio.',
diff --git a/dictionaries/fr.dictionary.itop.ui.php b/dictionaries/fr.dictionary.itop.ui.php
index 344c75b98..c39162895 100644
--- a/dictionaries/fr.dictionary.itop.ui.php
+++ b/dictionaries/fr.dictionary.itop.ui.php
@@ -451,6 +451,8 @@ Dict::Add('FR FR', 'French', 'Français', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance',
 	'UI:Error:InvalidToken' => 'Erreur: l\'opération a déjà été effectuée (CSRF token not found)',
 
+	'UI:Error:SMTP:UnknownVendor' => 'Le provider SMTP Oauth 2.0 %1$s n\'existe pas',
+
 	'UI:GroupBy:Count' => 'Nombre',
 	'UI:GroupBy:Count+' => 'Nombre d\'éléments',
 	'UI:CountOfObjects' => '%1$d objets correspondants aux critères.',
diff --git a/dictionaries/hu.dictionary.itop.ui.php b/dictionaries/hu.dictionary.itop.ui.php
index b7b048515..8c8d2d0a6 100755
--- a/dictionaries/hu.dictionary.itop.ui.php
+++ b/dictionaries/hu.dictionary.itop.ui.php
@@ -451,6 +451,8 @@ Dict::Add('HU HU', 'Hungarian', 'Magyar', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Számossága',
 	'UI:GroupBy:Count+' => '',
 	'UI:CountOfObjects' => '%1$d darab objektum felel meg a kritériumoknak.',
diff --git a/dictionaries/it.dictionary.itop.ui.php b/dictionaries/it.dictionary.itop.ui.php
index f1a4f99c0..010995b19 100644
--- a/dictionaries/it.dictionary.itop.ui.php
+++ b/dictionaries/it.dictionary.itop.ui.php
@@ -464,6 +464,8 @@ Dict::Add('IT IT', 'Italian', 'Italiano', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Conteggio',
 	'UI:GroupBy:Count+' => '',
 	'UI:CountOfObjects' => '%1$d oggetti corrispondenti ai criteri.',
diff --git a/dictionaries/ja.dictionary.itop.ui.php b/dictionaries/ja.dictionary.itop.ui.php
index e30db1132..ec58e1697 100644
--- a/dictionaries/ja.dictionary.itop.ui.php
+++ b/dictionaries/ja.dictionary.itop.ui.php
@@ -451,6 +451,8 @@ Dict::Add('JA JP', 'Japanese', '日本語', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'カウント',
 	'UI:GroupBy:Count+' => '要素数',
 	'UI:CountOfObjects' => '%1$d 個のオブジェクトが条件にマッチしました。',
diff --git a/dictionaries/nl.dictionary.itop.ui.php b/dictionaries/nl.dictionary.itop.ui.php
index 3c269cb75..011056ed1 100644
--- a/dictionaries/nl.dictionary.itop.ui.php
+++ b/dictionaries/nl.dictionary.itop.ui.php
@@ -470,6 +470,8 @@ Dict::Add('NL NL', 'Dutch', 'Nederlands', array(
 	'UI:Error:MaintenanceTitle' => 'Onderhoud',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Aantal',
 	'UI:GroupBy:Count+' => 'Aantal objecten',
 	'UI:CountOfObjects' => '%1$d objecten voldoen aan de criteria.',
diff --git a/dictionaries/pt_br.dictionary.itop.ui.php b/dictionaries/pt_br.dictionary.itop.ui.php
index c0d934124..6a51d4410 100644
--- a/dictionaries/pt_br.dictionary.itop.ui.php
+++ b/dictionaries/pt_br.dictionary.itop.ui.php
@@ -464,6 +464,8 @@ Dict::Add('PT BR', 'Brazilian', 'Brazilian', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Número',
 	'UI:GroupBy:Count+' => 'Número de elementos',
 	'UI:CountOfObjects' => '%1$d objetos correspondem aos critérios.',
diff --git a/dictionaries/ru.dictionary.itop.ui.php b/dictionaries/ru.dictionary.itop.ui.php
index 1a10d0b74..c2b968113 100644
--- a/dictionaries/ru.dictionary.itop.ui.php
+++ b/dictionaries/ru.dictionary.itop.ui.php
@@ -443,6 +443,8 @@ Dict::Add('RU RU', 'Russian', 'Русский', array(
 	'UI:Error:MaintenanceTitle' => 'Техническое обслуживание',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Количество',
 	'UI:GroupBy:Count+' => 'Количество элементов',
 	'UI:CountOfObjects' => '%1$d объектов соответствует критериям.',
diff --git a/dictionaries/sk.dictionary.itop.ui.php b/dictionaries/sk.dictionary.itop.ui.php
index 74290f499..854232778 100644
--- a/dictionaries/sk.dictionary.itop.ui.php
+++ b/dictionaries/sk.dictionary.itop.ui.php
@@ -451,6 +451,8 @@ Dict::Add('SK SK', 'Slovak', 'Slovenčina', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Počet',
 	'UI:GroupBy:Count+' => '',
 	'UI:CountOfObjects' => '%1$d objekt/y/ov sa nezhoduje s kritériami.',
diff --git a/dictionaries/tr.dictionary.itop.ui.php b/dictionaries/tr.dictionary.itop.ui.php
index f87d86e6b..32a7015d3 100644
--- a/dictionaries/tr.dictionary.itop.ui.php
+++ b/dictionaries/tr.dictionary.itop.ui.php
@@ -465,6 +465,8 @@ Dict::Add('TR TR', 'Turkish', 'Türkçe', array(
 	'UI:Error:MaintenanceTitle' => 'Maintenance~~',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => 'Say',
 	'UI:GroupBy:Count+' => 'Eleman sayısı',
 	'UI:CountOfObjects' => 'Kritere uyan %1$d nesne bulundu.',
diff --git a/dictionaries/zh_cn.dictionary.itop.ui.php b/dictionaries/zh_cn.dictionary.itop.ui.php
index ee498ef97..fc2cbd798 100644
--- a/dictionaries/zh_cn.dictionary.itop.ui.php
+++ b/dictionaries/zh_cn.dictionary.itop.ui.php
@@ -464,6 +464,8 @@ Dict::Add('ZH CN', 'Chinese', '简体中文', array(
 	'UI:Error:MaintenanceTitle' => '维护',
 	'UI:Error:InvalidToken' => 'Error: the requested operation has already been performed (CSRF token not found)~~',
 
+	'UI:Error:SMTP:UnknownVendor' => 'OAuth SMTP provider %1$s does not exist  (email_transport_smtp.oauth.provider)~~',
+
 	'UI:GroupBy:Count' => '个数',
 	'UI:GroupBy:Count+' => '元素数量',
 	'UI:CountOfObjects' => '%1$d 个对象符合指定的条件.',
diff --git a/sources/Core/Authentication/Client/OAuth/OAuthClientProviderFactory.php b/sources/Core/Authentication/Client/OAuth/OAuthClientProviderFactory.php
index 8ede0f6fe..d484b26ba 100644
--- a/sources/Core/Authentication/Client/OAuth/OAuthClientProviderFactory.php
+++ b/sources/Core/Authentication/Client/OAuth/OAuthClientProviderFactory.php
@@ -2,47 +2,68 @@
 
 namespace Combodo\iTop\Core\Authentication\Client\OAuth;
 
+use CoreException;
+use Dict;
 use GuzzleHttp\Client;
 use League\OAuth2\Client\Token\AccessTokenInterface;
 use MetaModel;
 
-class OAuthClientProviderFactory {
+class OAuthClientProviderFactory
+{
+	/**
+	 * @return mixed
+	 * @throws \CoreException
+	 */
 	public static function getProviderForSMTP()
 	{
 		$sProviderVendor = MetaModel::GetConfig()->Get('email_transport_smtp.oauth.provider'); // email_transport_smtp.oauth.provider
-		$sProviderClass = "\Combodo\iTop\Core\Authentication\Client\OAuth\OAuthClientProvider".$sProviderVendor;
+		$sProviderClass = self::getProviderClass($sProviderVendor);
 		$aProviderVendorParams = [
 			'clientId'     => MetaModel::GetConfig()->Get('email_transport_smtp.oauth.client_id'),  // email_transport_smtp.oauth.client_id
 			'clientSecret' => MetaModel::GetConfig()->Get('email_transport_smtp.oauth.client_secret'),// email_transport_smtp.oauth.client_secret
 			'redirectUri'  => $sProviderClass::GetRedirectUri(),
-			'scope' => $sProviderClass::GetRequiredSMTPScope()
+			'scope'        => $sProviderClass::GetRequiredSMTPScope(),
 		];
 		$aAccessTokenParams = [
 			"access_token"  => MetaModel::GetConfig()->Get('email_transport_smtp.oauth.access_token'), // email_transport_smtp.oauth.access_token
 			"refresh_token" => MetaModel::GetConfig()->Get('email_transport_smtp.oauth.refresh_token'), // email_transport_smtp.oauth.refresh_token
-			'scope' => $sProviderClass::GetRequiredSMTPScope()
+			'scope'         => $sProviderClass::GetRequiredSMTPScope(),
 		];
 		$aCollaborators = [
 			'httpClient' => new Client(['verify' => false]),
 		];
-		
+
 		return new $sProviderClass($aProviderVendorParams, $aCollaborators, $aAccessTokenParams);
 	}
-	public static function getVendorProvider($sProviderVendor, $sClientId, $sClientSecret, $sScope, $aAdditional){
+
+	/**
+	 * @param $sProviderVendor
+	 * @param $sClientId
+	 * @param $sClientSecret
+	 * @param $sScope
+	 * @param $aAdditional
+	 *
+	 * @return mixed
+	 * @throws \CoreException
+	 */
+	public static function getVendorProvider($sProviderVendor, $sClientId, $sClientSecret, $sScope, $aAdditional)
+	{
 		$sRedirectUrl = OAuthClientProviderAbstract::GetRedirectUri();
-		$sProviderClass = "\Combodo\iTop\Core\Authentication\Client\OAuth\OAuthClientProvider".$sProviderVendor;
+		$sProviderClass = self::getProviderClass($sProviderVendor);
 		$aCollaborators = [
 			'httpClient' => new Client(['verify' => false]),
 		];
 
 		return new $sProviderClass(array_merge(['clientId' => $sClientId, 'clientSecret' => $sClientSecret, 'redirectUri' => $sRedirectUrl, 'scope' => $sScope], $aAdditional), $aCollaborators);
 	}
-	
-	public static function getVendorProviderForAccessUrl($sProviderVendor, $sClientId, $sClientSecret, $sScope, $aAdditional){
+
+	public static function getVendorProviderForAccessUrl($sProviderVendor, $sClientId, $sClientSecret, $sScope, $aAdditional)
+	{
 		$oProvider = static::getVendorProvider($sProviderVendor, $sClientId, $sClientSecret, $sScope, $aAdditional);
+
 		return $oProvider->GetVendorProvider()->getAuthorizationUrl([
 			'scope' => [
-				$sScope
+				$sScope,
 			],
 		]);
 	}
@@ -58,16 +79,33 @@ class OAuthClientProviderFactory {
 	{
 		return $oProvider->GetVendorProvider()->getAccessToken('authorization_code', ['code' => $sCode, 'scope' => $oProvider->GetScope()]);
 	}
-	
+
 	public static function getConfFromRedirectUrl($sProviderVendor, $sClientId, $sClientSecret, $sRedirectUrlQuery)
 	{
 		$sRedirectUrl = OAuthClientProviderAbstract::GetRedirectUri();
-		$sProviderClass = "\Combodo\iTop\Core\Authentication\Client\OAuth\OAuthClientProvider".$sProviderVendor;
+		$sProviderClass = self::getProviderClass($sProviderVendor);
 		$aQuery = [];
 		parse_str($sRedirectUrlQuery, $aQuery);
 		$sCode = $aQuery['code'];
 		$oProvider = new $sProviderClass(['clientId' => $sClientId, 'clientSecret' => $sClientSecret, 'redirectUri' => $sRedirectUrl]);
+
 		return $sProviderClass::getConfFromAccessToken($oProvider->GetVendorProvider()->getAccessToken('authorization_code', ['code' => $sCode]), $sClientId, $sClientSecret);
 	}
 
+	/**
+	 * @param $sProviderVendor
+	 *
+	 * @return string
+	 * @throws \CoreException
+	 */
+	public static function getProviderClass($sProviderVendor): string
+	{
+		$sProviderClass = "\Combodo\iTop\Core\Authentication\Client\OAuth\OAuthClientProvider".$sProviderVendor;
+		if (!class_exists($sProviderClass)) {
+			throw new CoreException(dict::Format('UI:Error:SMTP:UnknownVendor', $sProviderVendor));
+		}
+
+		return $sProviderClass;
+	}
+
 }
\ No newline at end of file