--- a/src/mail/ngx_mail_parse.c
+++ b/src/mail/ngx_mail_parse.c
@@ -825,3 +825,56 @@ invalid:
 
     return NGX_MAIL_PARSE_INVALID_COMMAND;
 }
+
+
+ngx_int_t
+ngx_mail_auth_parse(ngx_mail_session_t *s, ngx_connection_t *c)
+{
+    ngx_str_t                 *arg;
+
+#if (NGX_MAIL_SSL)
+    if (ngx_mail_starttls_only(s, c)) {
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+#endif
+
+    arg = s->args.elts;
+
+    if (arg[0].len == 5) {
+
+        if (ngx_strncasecmp(arg[0].data, (u_char *) "LOGIN", 5) == 0) {
+
+            if (s->args.nelts == 1) {
+                return NGX_MAIL_AUTH_LOGIN;
+            }
+
+            return NGX_MAIL_PARSE_INVALID_COMMAND;
+        }
+
+        if (ngx_strncasecmp(arg[0].data, (u_char *) "PLAIN", 5) == 0) {
+
+            if (s->args.nelts == 1) {
+                return NGX_MAIL_AUTH_PLAIN;
+            }
+
+            if (s->args.nelts == 2) {
+                return ngx_mail_auth_plain(s, c, 1);
+            }
+        }
+
+        return NGX_MAIL_PARSE_INVALID_COMMAND;
+    }
+
+    if (arg[0].len == 8) {
+
+        if (s->args.nelts != 1) {
+            return NGX_MAIL_PARSE_INVALID_COMMAND;
+        }
+
+        if (ngx_strncasecmp(arg[0].data, (u_char *) "CRAM-MD5", 8) == 0) {
+            return NGX_MAIL_AUTH_CRAM_MD5;
+        }
+    }
+
+    return NGX_MAIL_PARSE_INVALID_COMMAND;
+}