Fix warnings

htdocs/core/class/CMailFile.class.php

@@ -298,7 +298,7 @@ class CMailFile
 		if (!empty($this->sendcontext)) {
 			$smtpContextKey = strtoupper($this->sendcontext);
 			$keyForSMTPSendMode = 'MAIN_MAIL_SENDMODE_'.$smtpContextKey;
-			$smtpContextSendMode = $conf->global->{$keyForSMTPSendMode};
+			$smtpContextSendMode = empty($conf->global->{$keyForSMTPSendMode}) ? '' : $conf->global->{$keyForSMTPSendMode};
 			if (!empty($smtpContextSendMode) && $smtpContextSendMode != 'default') {
 				$keyforsslseflsigned = 'MAIN_MAIL_EMAIL_SMTP_ALLOW_SELF_SIGNED_'.$smtpContextKey;
 			}
@@ -657,7 +657,7 @@ class CMailFile
 			if (!empty($this->sendcontext)) {
 				$smtpContextKey = strtoupper($this->sendcontext);
 				$keyForSMTPSendMode = 'MAIN_MAIL_SENDMODE_'.$smtpContextKey;
-				$smtpContextSendMode = $conf->global->{$keyForSMTPSendMode};
+				$smtpContextSendMode = empty($conf->global->{$keyForSMTPSendMode}) ? '' : $conf->global->{$keyForSMTPSendMode};
 				if (!empty($smtpContextSendMode) && $smtpContextSendMode != 'default') {
 					$keyforsmtpserver = 'MAIN_MAIL_SMTP_SERVER_'.$smtpContextKey;
 					$keyforsmtpport   = 'MAIN_MAIL_SMTP_PORT_'.$smtpContextKey;