--- a/src/imap/ngx_imap.h
+++ b/src/imap/ngx_imap.h
@@ -83,6 +83,8 @@ typedef struct {
 
     ngx_str_t               pop3_capability;
     ngx_str_t               pop3_starttls_capability;
+    ngx_str_t               pop3_auth_capability;
+
     ngx_str_t               imap_capability;
     ngx_str_t               imap_starttls_capability;
     ngx_str_t               imap_starttls_only_capability;
@@ -120,7 +122,11 @@ typedef enum {
 typedef enum {
     ngx_pop3_start = 0,
     ngx_pop3_user,
-    ngx_pop3_passwd
+    ngx_pop3_passwd,
+    ngx_pop3_auth_login_username,
+    ngx_pop3_auth_login_password,
+    ngx_pop3_auth_plain,
+    ngx_pop3_auth_cram_md5
 } ngx_po3_state_e;
 
 
@@ -153,7 +159,7 @@ typedef struct {
     unsigned                backslash:1;
     unsigned                no_sync_literal:1;
     unsigned                starttls:1;
-    unsigned                auth_method:1;
+    unsigned                auth_method:2;
 
     ngx_str_t               login;
     ngx_str_t               passwd;
@@ -192,13 +198,14 @@ typedef struct {
 #define NGX_POP3_NOOP        5
 #define NGX_POP3_STLS        6
 #define NGX_POP3_APOP        7
-#define NGX_POP3_STAT        8
-#define NGX_POP3_LIST        9
-#define NGX_POP3_RETR        10
-#define NGX_POP3_DELE        11
-#define NGX_POP3_RSET        12
-#define NGX_POP3_TOP         13
-#define NGX_POP3_UIDL        14
+#define NGX_POP3_AUTH        8
+#define NGX_POP3_STAT        9
+#define NGX_POP3_LIST        10
+#define NGX_POP3_RETR        11
+#define NGX_POP3_DELE        12
+#define NGX_POP3_RSET        13
+#define NGX_POP3_TOP         14
+#define NGX_POP3_UIDL        15
 
 
 #define NGX_IMAP_LOGIN       1
@@ -210,12 +217,14 @@ typedef struct {
 #define NGX_IMAP_NEXT        6
 
 
-#define NGX_IMAP_AUTH_PLAIN  0
-#define NGX_IMAP_AUTH_APOP   1
+#define NGX_IMAP_AUTH_PLAIN     0
+#define NGX_IMAP_AUTH_APOP      1
+#define NGX_IMAP_AUTH_CRAM_MD5  2
 
 
-#define NGX_IMAP_AUTH_PLAIN_ENABLED  0x0002
-#define NGX_IMAP_AUTH_APOP_ENABLED   0x0004
+#define NGX_IMAP_AUTH_PLAIN_ENABLED     0x0002
+#define NGX_IMAP_AUTH_APOP_ENABLED      0x0004
+#define NGX_IMAP_AUTH_CRAM_MD5_ENABLED  0x0008
 
 
 #define NGX_IMAP_PARSE_INVALID_COMMAND  20

--- a/src/imap/ngx_imap_auth_http_module.c
+++ b/src/imap/ngx_imap_auth_http_module.c
@@ -133,7 +133,9 @@ ngx_module_t  ngx_imap_auth_http_module 
 
 static char       *ngx_imap_auth_http_protocol[] = { "pop3", "imap" };
 static ngx_str_t   ngx_imap_auth_http_method[] = {
-    ngx_string("plain"), ngx_string("apop")
+    ngx_string("plain"),
+    ngx_string("apop"),
+    ngx_string("cram-md5")
 };
 
 
@@ -1078,7 +1080,7 @@ ngx_imap_auth_http_create_request(ngx_im
     b->last = ngx_copy(b->last, passwd.data, passwd.len);
     *b->last++ = CR; *b->last++ = LF;
 
-    if (s->salt.len) {
+    if (s->auth_method != NGX_IMAP_AUTH_PLAIN && s->salt.len) {
         b->last = ngx_cpymem(b->last, "Auth-Salt: ", sizeof("Auth-Salt: ") - 1);
         b->last = ngx_copy(b->last, s->salt.data, s->salt.len);
 

--- a/src/imap/ngx_imap_core_module.c
+++ b/src/imap/ngx_imap_core_module.c
@@ -48,10 +48,27 @@ static ngx_str_t  ngx_imap_default_capab
 static ngx_conf_bitmask_t  ngx_imap_auth_methods[] = {
     { ngx_string("plain"), NGX_IMAP_AUTH_PLAIN_ENABLED },
     { ngx_string("apop"), NGX_IMAP_AUTH_APOP_ENABLED },
+    { ngx_string("cram-md5"), NGX_IMAP_AUTH_CRAM_MD5_ENABLED },
     { ngx_null_string, 0 }
 };
 
 
+static ngx_str_t  ngx_pop3_auth_plain_capability =
+    ngx_string("+OK methods supported:" CRLF
+               "LOGIN" CRLF
+               "PLAIN" CRLF
+               "." CRLF);
+
+
+static ngx_str_t  ngx_pop3_auth_cram_md5_capability =
+    ngx_string("+OK methods supported:" CRLF
+               "LOGIN" CRLF
+               "PLAIN" CRLF
+               "CRAM-MD5" CRLF
+               "." CRLF);
+
+
+
 static ngx_command_t  ngx_imap_core_commands[] = {
 
     { ngx_string("server"),
@@ -279,6 +296,13 @@ ngx_imap_core_merge_srv_conf(ngx_conf_t 
         size += c[i].len + sizeof(CRLF) - 1;
     }
 
+    if (conf->auth_methods & NGX_IMAP_AUTH_CRAM_MD5_ENABLED) {
+        size += sizeof("SASL LOGIN PLAIN CRAM-MD5" CRLF) - 1;
+
+    } else {
+        size += sizeof("SASL LOGIN PLAIN" CRLF) - 1;
+    }
+
     p = ngx_palloc(cf->pool, size);
     if (p == NULL) {
         return NGX_CONF_ERROR;
@@ -295,6 +319,15 @@ ngx_imap_core_merge_srv_conf(ngx_conf_t 
         *p++ = CR; *p++ = LF;
     }
 
+    if (conf->auth_methods & NGX_IMAP_AUTH_CRAM_MD5_ENABLED) {
+        p = ngx_cpymem(p, "SASL LOGIN PLAIN CRAM-MD5" CRLF,
+                       sizeof("SASL LOGIN PLAIN CRAM-MD5" CRLF) - 1);
+
+    } else {
+        p = ngx_cpymem(p, "SASL LOGIN PLAIN" CRLF,
+                       sizeof("SASL LOGIN PLAIN" CRLF) - 1);
+    }
+
     *p++ = '.'; *p++ = CR; *p = LF;
 
 
@@ -315,6 +348,14 @@ ngx_imap_core_merge_srv_conf(ngx_conf_t 
     *p++ = '.'; *p++ = CR; *p = LF;
 
 
+    if (conf->auth_methods & NGX_IMAP_AUTH_CRAM_MD5_ENABLED) {
+        conf->pop3_auth_capability = ngx_pop3_auth_cram_md5_capability;
+
+    } else {
+        conf->pop3_auth_capability = ngx_pop3_auth_plain_capability;
+    }
+
+
     if (conf->imap_capabilities.nelts == 0) {
         conf->imap_capabilities = prev->imap_capabilities;
     }

--- a/src/imap/ngx_imap_handler.c
+++ b/src/imap/ngx_imap_handler.c
@@ -32,6 +32,9 @@ static ngx_str_t  internal_server_errors
 };
 
 static u_char  pop3_ok[] = "+OK" CRLF;
+static u_char  pop3_next[] = "+ " CRLF;
+static u_char  pop3_username[] = "+ VXNlcm5hbWU6" CRLF;
+static u_char  pop3_password[] = "+ UGFzc3dvcmQ6" CRLF;
 static u_char  pop3_invalid_command[] = "-ERR invalid command" CRLF;
 
 static u_char  imap_star[] = "* ";
@@ -547,11 +550,9 @@ ngx_imap_auth_state(ngx_event_t *rev)
                 ngx_imap_auth_http_init(s);
 
                 return;
-
-            } else {
-                rc = NGX_IMAP_PARSE_INVALID_COMMAND;
             }
 
+            rc = NGX_IMAP_PARSE_INVALID_COMMAND;
             break;
 
         case NGX_IMAP_CAPABILITY:
@@ -666,10 +667,10 @@ ngx_imap_auth_state(ngx_event_t *rev)
 void
 ngx_pop3_auth_state(ngx_event_t *rev)
 {
-    u_char                    *text;
+    u_char                    *text, *p, *last;
     ssize_t                    size;
     ngx_int_t                  rc;
-    ngx_str_t                 *arg;
+    ngx_str_t                 *arg, salt, plain;
     ngx_connection_t          *c;
     ngx_imap_session_t        *s;
     ngx_imap_core_srv_conf_t  *cscf;
@@ -730,10 +731,10 @@ ngx_pop3_auth_state(ngx_event_t *rev)
                     ngx_log_debug1(NGX_LOG_DEBUG_IMAP, c->log, 0,
                                    "pop3 login: \"%V\"", &s->login);
 
-                } else {
-                    rc = NGX_IMAP_PARSE_INVALID_COMMAND;
+                    break;
                 }
 
+                rc = NGX_IMAP_PARSE_INVALID_COMMAND;
                 break;
 
             case NGX_POP3_CAPA:
@@ -799,11 +800,78 @@ ngx_pop3_auth_state(ngx_event_t *rev)
                     ngx_imap_auth_http_init(s);
 
                     return;
+                }
 
-                } else {
+                rc = NGX_IMAP_PARSE_INVALID_COMMAND;
+                break;
+
+            case NGX_POP3_AUTH:
+                cscf = ngx_imap_get_module_srv_conf(s, ngx_imap_core_module);
+
+                if (s->args.nelts == 0) {
+                    size = cscf->pop3_auth_capability.len;
+                    text = cscf->pop3_auth_capability.data;
+                    break;
+                }
+
+                if (s->args.nelts != 1) {
                     rc = NGX_IMAP_PARSE_INVALID_COMMAND;
+                    break;
                 }
 
+                arg = s->args.elts;
+
+                s->args.nelts = 0;
+                s->buffer->pos = s->buffer->start;
+                s->buffer->last = s->buffer->start;
+                s->arg_start = s->buffer->start;
+
+                if (arg[0].len == 5) {
+
+                    if (ngx_strncasecmp(arg[0].data, "LOGIN", 5) == 0) {
+                        s->imap_state = ngx_pop3_auth_login_username;
+
+                        size = sizeof(pop3_username) - 1;
+                        text = pop3_username;
+
+                        break;
+
+                    } else if (ngx_strncasecmp(arg[0].data, "PLAIN", 5) == 0) {
+                        s->imap_state = ngx_pop3_auth_plain;
+
+                        size = sizeof(pop3_next) - 1;
+                        text = pop3_next;
+
+                        break;
+                    }
+
+                } else if (arg[0].len == 8
+                           && ngx_strncasecmp(arg[0].data, "CRAM-MD5", 8) == 0)
+                {
+                    s->imap_state = ngx_pop3_auth_cram_md5;
+
+                    text = ngx_palloc(c->pool,
+                                 sizeof("+ " CRLF) - 1
+                                 + ngx_base64_encoded_length(s->salt.len));
+                    if (text == NULL) {
+                        ngx_imap_session_internal_server_error(s);
+                        return;
+                    }
+
+                    text[0] = '+'; text[1]= ' ';
+                    salt.data = &text[2];
+                    s->salt.len -= 2;
+
+                    ngx_encode_base64(&salt, &s->salt);
+
+                    s->salt.len += 2;
+                    size = 2 + salt.len;
+                    text[size++] = CR; text[size++] = LF;
+
+                    break;
+                }
+
+                rc = NGX_IMAP_PARSE_INVALID_COMMAND;
                 break;
 
             case NGX_POP3_QUIT:
@@ -869,11 +937,9 @@ ngx_pop3_auth_state(ngx_event_t *rev)
                     ngx_imap_auth_http_init(s);
 
                     return;
-
-                } else {
-                    rc = NGX_IMAP_PARSE_INVALID_COMMAND;
                 }
 
+                rc = NGX_IMAP_PARSE_INVALID_COMMAND;
                 break;
 
             case NGX_POP3_CAPA:
@@ -900,6 +966,189 @@ ngx_pop3_auth_state(ngx_event_t *rev)
         /* suppress warinings */
         case ngx_pop3_passwd:
             break;
+
+        case ngx_pop3_auth_login_username:
+            arg = s->args.elts;
+            s->imap_state = ngx_pop3_auth_login_password;
+
+            s->args.nelts = 0;
+            s->buffer->pos = s->buffer->start;
+            s->buffer->last = s->buffer->start;
+            s->arg_start = s->buffer->start;
+
+            ngx_log_debug1(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth login username: \"%V\"", &arg[0]);
+
+            s->login.data = ngx_palloc(c->pool,
+                                       ngx_base64_decoded_length(arg[0].len));
+            if (s->login.data == NULL){
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+            if (ngx_decode_base64(&s->login, &arg[0]) != NGX_OK) {
+                ngx_log_error(NGX_LOG_INFO, c->log, 0,
+                              "client sent invalid base64 encoding "
+                              "in AUTH LOGIN command");
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+            ngx_log_debug1(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth login username: \"%V\"", &s->login);
+
+            size = sizeof(pop3_password) - 1;
+            text = pop3_password;
+
+            break;
+
+        case ngx_pop3_auth_login_password:
+            arg = s->args.elts;
+
+#if (NGX_DEBUG_IMAP_PASSWD)
+            ngx_log_debug1(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth login password: \"%V\"", &arg[0]);
+#endif
+
+            s->passwd.data = ngx_palloc(c->pool,
+                                        ngx_base64_decoded_length(arg[0].len));
+            if (s->passwd.data == NULL){
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+            if (ngx_decode_base64(&s->passwd, &arg[0]) != NGX_OK) {
+                ngx_log_error(NGX_LOG_INFO, c->log, 0,
+                              "client sent invalid base64 encoding "
+                              "in AUTH LOGIN command");
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+#if (NGX_DEBUG_IMAP_PASSWD)
+            ngx_log_debug1(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth login password: \"%V\"", &s->passwd);
+#endif
+
+            s->args.nelts = 0;
+            s->buffer->pos = s->buffer->start;
+            s->buffer->last = s->buffer->start;
+
+            if (rev->timer_set) {
+                ngx_del_timer(rev);
+            }
+
+            ngx_imap_auth_http_init(s);
+
+            return;
+
+        case ngx_pop3_auth_plain:
+            arg = s->args.elts;
+
+#if (NGX_DEBUG_IMAP_PASSWD)
+            ngx_log_debug1(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth plain: \"%V\"", &arg[0]);
+#endif
+
+            plain.data = ngx_palloc(c->pool,
+                                    ngx_base64_decoded_length(arg[0].len));
+            if (plain.data == NULL){
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+            if (ngx_decode_base64(&plain, &arg[0]) != NGX_OK) {
+                ngx_log_error(NGX_LOG_INFO, c->log, 0,
+                              "client sent invalid base64 encoding "
+                              "in AUTH PLAIN command");
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+            p = plain.data;
+            last = p + plain.len;
+
+            while (p < last && *p++) { /* void */ }
+
+            s->login.data = p;
+
+            while (p < last && *p) { p++; }
+
+            s->login.len = p++ - s->login.data;
+            s->passwd.data = p;
+
+            while (p < last && *p) { p++; }
+
+            s->passwd.len = p - s->passwd.data;
+
+#if (NGX_DEBUG_IMAP_PASSWD)
+            ngx_log_debug2(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth plain: \"%V\" \"%V\"",
+                           &s->login, &s->passwd);
+#endif
+
+            s->args.nelts = 0;
+            s->buffer->pos = s->buffer->start;
+            s->buffer->last = s->buffer->start;
+
+            if (rev->timer_set) {
+                ngx_del_timer(rev);
+            }
+
+            ngx_imap_auth_http_init(s);
+
+            return;
+
+        case ngx_pop3_auth_cram_md5:
+            arg = s->args.elts;
+
+            ngx_log_debug1(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth cram-md5: \"%V\"", &arg[0]);
+
+            s->login.data = ngx_palloc(c->pool,
+                                       ngx_base64_decoded_length(arg[0].len));
+            if (s->login.data == NULL){
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+            if (ngx_decode_base64(&s->login, &arg[0]) != NGX_OK) {
+                ngx_log_error(NGX_LOG_INFO, c->log, 0,
+                              "client sent invalid base64 encoding "
+                              "in AUTH LOGIN command");
+                ngx_imap_session_internal_server_error(s);
+                return;
+            }
+
+            p = s->login.data;
+            last = p + s->login.len;
+
+            while (p < last) {
+                if (*p++ == ' ') {
+                    s->login.len = p - s->login.data - 1;
+                    s->passwd.len = last - p;
+                    s->passwd.data = p;
+                    break;
+                }
+            }
+
+            ngx_log_debug2(NGX_LOG_DEBUG_IMAP, c->log, 0,
+                           "pop3 auth cram-md5: \"%V\" \"%V\"",
+                           &s->login, &s->passwd);
+
+            s->auth_method = NGX_IMAP_AUTH_CRAM_MD5;
+
+            s->args.nelts = 0;
+            s->buffer->pos = s->buffer->start;
+            s->buffer->last = s->buffer->start;
+
+            if (rev->timer_set) {
+                ngx_del_timer(rev);
+            }
+
+            ngx_imap_auth_http_init(s);
+
+            return;
         }
     }
 

--- a/src/imap/ngx_imap_parse.c
+++ b/src/imap/ngx_imap_parse.c
@@ -441,6 +441,10 @@ ngx_int_t ngx_pop3_parse_command(ngx_ima
                     {
                         s->command = NGX_POP3_CAPA;
 
+                    } else if (c0 == 'A' && c1 == 'U' && c2 == 'T' && c3 == 'H')
+                    {
+                        s->command = NGX_POP3_AUTH;
+
                     } else if (c0 == 'N' && c1 == 'O' && c2 == 'O' && c3 == 'P')
                     {
                         s->command = NGX_POP3_NOOP;
@@ -571,8 +575,7 @@ done:
         s->arg_start = NULL;
     }
 
-    s->state = sw_start;
-
+    s->state = (s->command != NGX_POP3_AUTH) ? sw_start : sw_argument;
     return NGX_OK;
 
 invalid: