diff --git a/notify/smtp.sh b/notify/smtp.sh
index 6aa37ca3..4c06bd3d 100644
--- a/notify/smtp.sh
+++ b/notify/smtp.sh
@@ -1,15 +1,83 @@
 #!/usr/bin/env sh
 
-# support smtp
-
 smtp_send() {
-  _subject="$1"
-  _content="$2"
-  _statusCode="$3" #0: success, 1: error 2($RENEW_SKIP): skipped
+  if ! _exists "mailx"; then
+    _err "You must install mailx to send email by SMTP"
+    return 1
+  fi
+
+  SMTP_FROM="${SMTP_FROM:-$(_readaccountconf_mutable SMTP_FROM)}"
+  if [ -z "$SMTP_FROM" ]; then
+    _err "You must define SMTP_FROM as the sender email address."
+    return 1
+  fi
+
+  SMTP_TO="${SMTP_TO:-$(_readaccountconf_mutable SMTP_TO)}"
+  if [ -z "$SMTP_TO" ]; then
+    _err "You must define SMTP_TO as the recipient email address."
+    return 1
+  fi
+
+  SMTP_HOST="${SMTP_HOST:-$(_readaccountconf_mutable SMTP_HOST)}"
+  if [ -z "$SMTP_HOST" ]; then
+    _err "You must define SMTP_HOST as the SMTP server hostname."
+    return 1
+  fi
+
+  SMTP_USERNAME="${SMTP_USERNAME:-$(_readaccountconf_mutable SMTP_USERNAME)}"
+  SMTP_PASSWORD="${SMTP_PASSWORD:-$(_readaccountconf_mutable SMTP_PASSWORD)}"
+  SMTP_CONTEXT="${SMTP_CONTEXT:-$(_readaccountconf_mutable SMTP_CONTEXT)}"
+
+  _saveaccountconf_mutable SMTP_FROM "$SMTP_FROM"
+  _saveaccountconf_mutable SMTP_TO "$SMTP_TO"
+  _saveaccountconf_mutable SMTP_HOST "$SMTP_HOST"
+  _saveaccountconf_mutable SMTP_USERNAME "$SMTP_USERNAME"
+  _saveaccountconf_mutable SMTP_PASSWORD "$SMTP_PASSWORD"
+  _saveaccountconf_mutable SMTP_CONTEXT "$SMTP_CONTEXT" "base64"
+
+  if ! _smtp_send "$@"; then
+    _err "$smtp_send_output"
+    return 1
+  fi
+
+  return 0
+}
+
+_smtp_send() {
+  _subject="${1}"
+  _content="${2}"
+  _statusCode="${3}"
   _debug "_subject" "$_subject"
   _debug "_content" "$_content"
   _debug "_statusCode" "$_statusCode"
 
-  _err "Not implemented yet."
-  return 1
+  _debug "SMTP_FROM" "$SMTP_FROM"
+  _debug "SMTP_TO" "$SMTP_TO"
+  _debug "SMTP_HOST" "$SMTP_HOST"
+  _debug "SMTP_USERNAME" "$SMTP_USERNAME"
+  _debug "SMTP_PASSWORD" "$SMTP_PASSWORD"
+
+  if [ "${DEBUG:-$DEBUG_LEVEL_NONE}" -ge "$DEBUG_LEVEL_2" ]; then
+    smtp_debug="True"
+  else
+    smtp_debug=""
+  fi
+
+  smtp_send_output="$(echo "${_content}" | mailx -v \
+                      -s "${_subject}" \
+                      -S ssl-verify=ignore\
+                      -S smtp="${SMTP_HOST}" \
+                      -S smtp-auth=login \
+                      -S smtp-auth-user="${SMTP_USERNAME}" \
+                      -S smtp-auth-password="${SMTP_PASSWORD}" \
+                      -S from="${SMTP_FROM}" \
+                      "${SMTP_TO}" 2>&1)"
+
+  _debug "smtp_send_output" "$smtp_send_output"
+
+  if [ $smtp_send_output =~ "message not sent" ]; then
+    return 1
+  else
+    return 0
+  fi
 }