diff --git a/lib/pop3/connection.js b/lib/pop3/connection.js
index 8644386a..ca585f2e 100644
--- a/lib/pop3/connection.js
+++ b/lib/pop3/connection.js
@@ -443,7 +443,7 @@ class POP3Connection extends EventEmitter {
         }
 
         if (!params.length) {
-            this.send('+');
+            this.send('+ ');
             this._nextHandler = (args, next) => this.authPlain(args, next);
             return next();
         }