Check SMTP

Mini HTTP service that takes a JSON with server information and check if it's accessible from the application and if it can receive emails.

Env

Key	Requirement	Explanation
SHARED_KEY	mandatory	Secret shared between main app and this one. (Needs to be sent in the header Authorization)
PORT	optional (default 80)	Port used for the application
SMTP_CN	optional (default hostname)	Common Name to use for client certificate when doing a STARTTLS
SMTP_FROM_SPOOF	optional (default spoof@amazon.com)	Email to check for SPF checks (spoofing this email as MAIL FROM)
SMTP_CONN_TIMEOUT	optional (30 seconds)	How long to wait for the SMTP server to answer
SMTP_OPT_TIMEOUT	optional (30 seconds)	How long to wait for the SMTP server to answer each command
TLS_MIN_VERSION	optional (TLS1.2)	Check TLS Table for acceptable values. This is used when doing a STARTTLS on server that supports it.

TLS

TLS Version	EnvVar
SSLv3.0	SSL30
TLSv1	TLS10
TLSv1.1	TLS11
TLS1.2	TLS12
TLS1.3	TLS13

Data

{
  "from": "bounce@myserver.com",
  "body": "Hello World\n Are you doing well ?\n\nTester",
  "subject": "Hello World",
  "server": {
    "server": "example.com",
    "port": 25,
    "mx": false,
    "test_email": "test@example.com"
  }
}

Key	Explanation
from	Address to use in the MAIL FROM
body	Body of the mail
subject	Subject of the mail
server.server	Server to check
server.port	Port to use to attempt the connection
server.mx	Instead of resolving the IP, resolve the MX of the server first then check IPs
server.test_email	Used as RCPT TO when doing SMTP checks

Response

Success

{
    "success": true,
    "hello_banner": "220 example.com ESMTP Postfix (Debian/GNU)",
    "tls_version": "VersionTLS12",
    "general_log": {
        "1/CONNECTION": "192.168.22.3:25",
        "2/EHLO": "tardis.example.com",
        "3/STARTTLS": "VersionTLS12",
        "4/MAIL FROM": "test@example.com",
        "5/RCPT TO": "me@example.com",
        "6/DATA": "\nHello World\nAre you doing well ?\n\nTester",
        "7/QUIT": ""
    },
    "spf_log": {
        "1/CONNECTION": "192.168.22.3:25",
        "2/EHLO": "tardis.zerospam.ca",
        "3/STARTTLS": "",
        "8/SPF-FAIL": "antoineaf@admincmd.com"
    }
}

Error

{
    "success": false,
    "hello_banner": "220 set.example.com ESMTP Postfix (Debian/GNU)",
    "tls_version": "VersionTLS12",
    "error_message": {
        "command": "STARTTLS",
        "error_msg": "x509: certificate is valid for example.com, not set.example.com"
    },
    "general_log": {
        "1/CONNECTION": "192.168.22.3:25",
        "2/EHLO": "tardis.example.com",
        "3/STARTTLS": ""       
    },
    "spf_log": {
    }
}