diff --git a/src/mail/ngx_mail_parse.c b/src/mail/ngx_mail_parse.c
index c4e8f0eae..e55010c60 100644
--- a/src/mail/ngx_mail_parse.c
+++ b/src/mail/ngx_mail_parse.c
@@ -21,6 +21,8 @@ ngx_mail_pop3_parse_command(ngx_mail_session_t *s)
     ngx_str_t  *arg;
     enum {
         sw_start = 0,
+        sw_command,
+        sw_invalid,
         sw_spaces_before_argument,
         sw_argument,
         sw_almost_done
@@ -35,8 +37,14 @@ ngx_mail_pop3_parse_command(ngx_mail_session_t *s)
 
         /* POP3 command */
         case sw_start:
+            s->cmd_start = p;
+            state = sw_command;
+
+            /* fall through */
+
+        case sw_command:
             if (ch == ' ' || ch == CR || ch == LF) {
-                c = s->buffer->start;
+                c = s->cmd_start;
 
                 if (p - c == 4) {
 
@@ -85,6 +93,9 @@ ngx_mail_pop3_parse_command(ngx_mail_session_t *s)
                     goto invalid;
                 }
 
+                s->cmd.data = s->cmd_start;
+                s->cmd.len = p - s->cmd_start;
+
                 switch (ch) {
                 case ' ':
                     state = sw_spaces_before_argument;
@@ -104,6 +115,9 @@ ngx_mail_pop3_parse_command(ngx_mail_session_t *s)
 
             break;
 
+        case sw_invalid:
+            goto invalid;
+
         case sw_spaces_before_argument:
             switch (ch) {
             case ' ':
@@ -205,10 +219,22 @@ done:
 
 invalid:
 
-    s->state = sw_start;
+    s->state = sw_invalid;
     s->arg_start = NULL;
 
-    return NGX_MAIL_PARSE_INVALID_COMMAND;
+    /* skip invalid command till LF */
+
+    for ( /* void */ ; p < s->buffer->last; p++) {
+        if (*p == LF) {
+            s->state = sw_start;
+            s->buffer->pos = p + 1;
+            return NGX_MAIL_PARSE_INVALID_COMMAND;
+        }
+    }
+
+    s->buffer->pos = p;
+
+    return NGX_AGAIN;
 }
 
 
diff --git a/src/mail/ngx_mail_pop3_handler.c b/src/mail/ngx_mail_pop3_handler.c
index edfd98681..226e7419b 100644
--- a/src/mail/ngx_mail_pop3_handler.c
+++ b/src/mail/ngx_mail_pop3_handler.c
@@ -262,6 +262,10 @@ ngx_mail_pop3_auth_state(ngx_event_t *rev)
         }
     }
 
+    if (s->buffer->pos < s->buffer->last) {
+        s->blocked = 1;
+    }
+
     switch (rc) {
 
     case NGX_DONE:
@@ -283,11 +287,14 @@ ngx_mail_pop3_auth_state(ngx_event_t *rev)
     case NGX_OK:
 
         s->args.nelts = 0;
-        s->buffer->pos = s->buffer->start;
-        s->buffer->last = s->buffer->start;
+
+        if (s->buffer->pos == s->buffer->last) {
+            s->buffer->pos = s->buffer->start;
+            s->buffer->last = s->buffer->start;
+        }
 
         if (s->state) {
-            s->arg_start = s->buffer->start;
+            s->arg_start = s->buffer->pos;
         }
 
         if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
@@ -400,6 +407,8 @@ ngx_mail_pop3_stls(ngx_mail_session_t *s, ngx_connection_t *c)
     if (c->ssl == NULL) {
         sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module);
         if (sslcf->starttls) {
+            s->buffer->pos = s->buffer->start;
+            s->buffer->last = s->buffer->start;
             c->read->handler = ngx_mail_starttls_handler;
             return NGX_OK;
         }
diff --git a/src/mail/ngx_mail_proxy_module.c b/src/mail/ngx_mail_proxy_module.c
index 38164af95..0f56d299e 100644
--- a/src/mail/ngx_mail_proxy_module.c
+++ b/src/mail/ngx_mail_proxy_module.c
@@ -327,6 +327,10 @@ ngx_mail_proxy_pop3_handler(ngx_event_t *rev)
         c->log->action = NULL;
         ngx_log_error(NGX_LOG_INFO, c->log, 0, "client logged in");
 
+        if (s->buffer->pos < s->buffer->last) {
+            ngx_post_event(c->write, &ngx_posted_events);
+        }
+
         ngx_mail_proxy_handler(s->connection->write);
 
         return;