--- a/src/mail/ngx_mail_core_module.c
+++ b/src/mail/ngx_mail_core_module.c
@@ -54,6 +54,14 @@ static ngx_conf_bitmask_t  ngx_pop3_auth
 };
 
 
+static ngx_conf_bitmask_t  ngx_imap_auth_methods[] = {
+    { ngx_string("plain"), NGX_MAIL_AUTH_PLAIN_ENABLED },
+    { ngx_string("login"), NGX_MAIL_AUTH_LOGIN_ENABLED },
+    { ngx_string("cram-md5"), NGX_MAIL_AUTH_CRAM_MD5_ENABLED },
+    { ngx_null_string, 0 }
+};
+
+
 static ngx_conf_bitmask_t  ngx_smtp_auth_methods[] = {
     { ngx_string("plain"), NGX_MAIL_AUTH_PLAIN_ENABLED },
     { ngx_string("login"), NGX_MAIL_AUTH_LOGIN_ENABLED },
@@ -62,6 +70,14 @@ static ngx_conf_bitmask_t  ngx_smtp_auth
 };
 
 
+static ngx_str_t  ngx_imap_auth_methods_names[] = {
+    ngx_string("AUTH=PLAIN"),
+    ngx_string("AUTH=LOGIN"),
+    ngx_null_string,  /* APOP */
+    ngx_string("AUTH=CRAM-MD5")
+};
+
+
 static ngx_str_t  ngx_smtp_auth_methods_names[] = {
     ngx_string("PLAIN"),
     ngx_string("LOGIN"),
@@ -172,6 +188,13 @@ static ngx_command_t  ngx_mail_core_comm
       offsetof(ngx_mail_core_srv_conf_t, pop3_auth_methods),
       &ngx_pop3_auth_methods },
 
+    { ngx_string("imap_auth"),
+      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_1MORE,
+      ngx_conf_set_bitmask_slot,
+      NGX_MAIL_SRV_CONF_OFFSET,
+      offsetof(ngx_mail_core_srv_conf_t, imap_auth_methods),
+      &ngx_imap_auth_methods },
+
     { ngx_string("smtp_auth"),
       NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_1MORE,
       ngx_conf_set_bitmask_slot,
@@ -278,7 +301,7 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
     ngx_mail_core_srv_conf_t *prev = parent;
     ngx_mail_core_srv_conf_t *conf = child;
 
-    u_char      *p;
+    u_char      *p, *auth;
     size_t       size, stls_only_size;
     ngx_str_t   *c, *d;
     ngx_uint_t   i, m;
@@ -297,6 +320,11 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
                                  (NGX_CONF_BITMASK_SET
                                   |NGX_MAIL_AUTH_PLAIN_ENABLED));
 
+    ngx_conf_merge_bitmask_value(conf->imap_auth_methods,
+                                 prev->imap_auth_methods,
+                                 (NGX_CONF_BITMASK_SET
+                                  |NGX_MAIL_AUTH_PLAIN_ENABLED));
+
     ngx_conf_merge_bitmask_value(conf->smtp_auth_methods,
                                  prev->smtp_auth_methods,
                                  (NGX_CONF_BITMASK_SET
@@ -463,6 +491,15 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
         size += 1 + c[i].len;
     }
 
+    for (m = NGX_MAIL_AUTH_PLAIN_ENABLED, i = 0;
+         m <= NGX_MAIL_AUTH_CRAM_MD5_ENABLED;
+         m <<= 1, i++)
+    {
+        if (m & conf->imap_auth_methods) {
+            size += 1 + ngx_imap_auth_methods_names[i].len;
+        }
+    }
+
     p = ngx_palloc(cf->pool, size);
     if (p == NULL) {
         return NGX_CONF_ERROR;
@@ -478,6 +515,19 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
         p = ngx_cpymem(p, c[i].data, c[i].len);
     }
 
+    auth = p;
+
+    for (m = NGX_MAIL_AUTH_PLAIN_ENABLED, i = 0;
+         m <= NGX_MAIL_AUTH_CRAM_MD5_ENABLED;
+         m <<= 1, i++)
+    {
+        if (m & conf->imap_auth_methods) {
+            *p++ = ' ';
+            p = ngx_cpymem(p, ngx_imap_auth_methods_names[i].data,
+                           ngx_imap_auth_methods_names[i].len);
+        }
+    }
+
     *p++ = CR; *p = LF;
 
 
@@ -497,7 +547,8 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
     *p++ = CR; *p = LF;
 
 
-    size += sizeof(" LOGINDISABLED") - 1;
+    size = (auth - conf->imap_capability.data) + sizeof(CRLF) - 1
+            + sizeof(" STARTTLS LOGINDISABLED") - 1;
 
     p = ngx_palloc(cf->pool, size);
     if (p == NULL) {
@@ -507,9 +558,10 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
     conf->imap_starttls_only_capability.len = size;
     conf->imap_starttls_only_capability.data = p;
 
-    p = ngx_cpymem(p, conf->imap_starttls_capability.data,
-                   conf->imap_starttls_capability.len - (sizeof(CRLF) - 1));
-    p = ngx_cpymem(p, " LOGINDISABLED", sizeof(" LOGINDISABLED") - 1);
+    p = ngx_cpymem(p, conf->imap_capability.data,
+                   auth - conf->imap_capability.data);
+    p = ngx_cpymem(p, " STARTTLS LOGINDISABLED",
+                   sizeof(" STARTTLS LOGINDISABLED") - 1);
     *p++ = CR; *p = LF;
 
 
@@ -582,6 +634,8 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
         *p++ = CR; *p++ = LF;
     }
 
+    auth = p;
+
     *p++ = '2'; *p++ = '5'; *p++ = '0'; *p++ = ' ';
     *p++ = 'A'; *p++ = 'U'; *p++ = 'T'; *p++ = 'H';
 
@@ -598,6 +652,42 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t 
 
     *p++ = CR; *p = LF;
 
+    size += sizeof("250 STARTTLS" CRLF) - 1;
+
+    p = ngx_palloc(cf->pool, size);
+    if (p == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    conf->smtp_starttls_capability.len = size;
+    conf->smtp_starttls_capability.data = p;
+
+    p = ngx_cpymem(p, conf->smtp_capability.data,
+                   conf->smtp_capability.len);
+
+    p = ngx_cpymem(p, "250 STARTTLS" CRLF, sizeof("250 STARTTLS" CRLF) - 1);
+    *p++ = CR; *p = LF;
+
+    p = conf->smtp_starttls_capability.data
+        + (auth - conf->smtp_capability.data) + 3;
+    *p = '-';
+
+    size = (auth - conf->smtp_capability.data)
+            + sizeof("250 STARTTLS" CRLF) - 1;
+
+    p = ngx_palloc(cf->pool, size);
+    if (p == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    conf->smtp_starttls_only_capability.len = size;
+    conf->smtp_starttls_only_capability.data = p;
+
+    p = ngx_cpymem(p, conf->smtp_capability.data,
+                   auth - conf->smtp_capability.data);
+
+    ngx_memcpy(p, "250 STARTTLS" CRLF, sizeof("250 STARTTLS" CRLF) - 1);
+
     return NGX_CONF_OK;
 }