diff --git a/sope-mime/NGMail/NGSmtpClient.m b/sope-mime/NGMail/NGSmtpClient.m
index 9b440a7..092b944 100644
--- a/sope-mime/NGMail/NGSmtpClient.m
+++ b/sope-mime/NGMail/NGSmtpClient.m
@@ -367,7 +367,7 @@
         self->extensions.hasPipelining = YES;
       else if ([line hasPrefix:@"HELP"])
         self->extensions.hasHelp = YES;
-      else if ([line hasPrefix:@"AUTH"]) {
+      else if ([line hasPrefix:@"AUTH "]) {
         NSArray *methods;
         methods = [line componentsSeparatedByString: @" "];
         self->extensions.hasAuthPlain = [methods containsObject: @"PLAIN"];