diff --git a/src/cfg.c b/src/cfg.c
index d3fa5e1e..1ce2ddd0 100644
--- a/src/cfg.c
+++ b/src/cfg.c
@@ -68,6 +68,7 @@ struct _parse_rule config_parse_rules[] =
    { "clamd_socket", "string", (void*) string_parser, offsetof(struct __config, clamd_socket), CLAMD_SOCKET, MAXVAL-1},
    { "debug", "integer", (void*) int_parser, offsetof(struct __config, debug), "0", sizeof(int)},
    { "default_retention_days", "integer", (void*) int_parser, offsetof(struct __config, default_retention_days), "2557", sizeof(int)},
+   { "enable_chunking", "integer", (void*) int_parser, offsetof(struct __config, enable_chunking), "0", sizeof(int)},
    { "enable_cjk", "integer", (void*) int_parser, offsetof(struct __config, enable_cjk), "0", sizeof(int)},
    { "enable_folders", "integer", (void*) int_parser, offsetof(struct __config, enable_folders), "0", sizeof(int)},
    { "encrypt_messages", "integer", (void*) int_parser, offsetof(struct __config, encrypt_messages), "1", sizeof(int)},
diff --git a/src/cfg.h b/src/cfg.h
index 47d74a29..8689d9ca 100644
--- a/src/cfg.h
+++ b/src/cfg.h
@@ -25,6 +25,7 @@ struct __config {
 
    int encrypt_messages;
 
+   int enable_chunking;
    int tls_enable;
    char pemfile[MAXVAL];
    char cipher_list[MAXVAL];
diff --git a/src/piler.c b/src/piler.c
index 7caf7ee4..ba6168ec 100644
--- a/src/piler.c
+++ b/src/piler.c
@@ -320,7 +320,7 @@ void initialise_configuration(){
    initrules(data.folder_rules);
 
    if(cfg.tls_enable > 0 && data.ctx == NULL && init_ssl() == OK){
-      snprintf(data.starttls, sizeof(data.starttls)-1, "250-STARTTLS\r\n");
+      snprintf(data.starttls, sizeof(data.starttls)-1, SMTP_EXTENSION_STARTTLS);
    }
 
    if(open_database(&sdata, &cfg) == ERR){
diff --git a/src/smtp.c b/src/smtp.c
index 636dd443..8be40007 100644
--- a/src/smtp.c
+++ b/src/smtp.c
@@ -22,11 +22,16 @@
 
 void process_command_ehlo_lhlo(struct session_data *sdata, struct __data *data, int *protocol_state, char *resp, int resplen, struct __config *cfg){
    char tmpbuf[MAXBUFSIZE];
+   char extensions[SMALLBUFSIZE];
+
+   memset(extensions, 0, sizeof(extensions));
 
    if(*protocol_state == SMTP_STATE_INIT) *protocol_state = SMTP_STATE_HELO;
 
-   if(sdata->tls == 0) snprintf(tmpbuf, sizeof(tmpbuf)-1, SMTP_RESP_250_EXTENSIONS, cfg->hostid, data->starttls);
-   else snprintf(tmpbuf, sizeof(tmpbuf)-1, SMTP_RESP_250_EXTENSIONS, cfg->hostid, "");
+   if(sdata->tls == 0) snprintf(extensions, sizeof(extensions)-1, "%s", data->starttls);
+   if(cfg->enable_chunking == 1) strncat(extensions, SMTP_EXTENSION_CHUNKING, sizeof(extensions)-strlen(extensions)-2);
+
+   snprintf(tmpbuf, sizeof(tmpbuf)-1, SMTP_RESP_250_EXTENSIONS, cfg->hostid, extensions);
 
    strncat(resp, tmpbuf, resplen-strlen(resp));
 }
diff --git a/src/smtpcodes.h b/src/smtpcodes.h
index 130136bb..038bd130 100644
--- a/src/smtpcodes.h
+++ b/src/smtpcodes.h
@@ -36,6 +36,9 @@
 #define SMTP_RESP_250_OK "250 Ok\r\n"
 #define SMTP_RESP_250_EXTENSIONS "250-%s\r\n250-PIPELINING\r\n%s250-SIZE\r\n250 8BITMIME\r\n"
 
+#define SMTP_EXTENSION_STARTTLS "250-STARTTLS\r\n"
+#define SMTP_EXTENSION_CHUNKING "250-CHUNKING\r\n"
+
 #define SMTP_RESP_354_DATA_OK "354 Send mail data; end it with <CRLF>.<CRLF>\r\n"
 
 #define SMTP_RESP_421_ERR "421 %s Error: timed out\r\n"