This test will connect to a mail server via SMTP, perform a simple Open Relay Test and verify the server has a reverse DNS (PTR) record. It will also measure the response times for the mail server. If you don't know your mail server's address, start with a MX Lookup .

All of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool. Input a domain name or IP Address or Host Name. Links in the results will guide you to other relevant tools and information.

MxToolbox offers free email server lookup tools and monitoring to alert you when you have a problem with your email server. The first step to fixing a problem with your mail server is identifying which issue it is currently experiencing, by running a smtp test.

The blacklist check will test a mail server IP address against over 100 DNS based email blacklists. (Commonly called Realtime blacklist, DNSBL or RBL). If your mail server has been blacklisted, some email you send may not be delivered. Email blacklists are a common way of reducing spam.

Monitor your Mail Server to ensure uptime and compliance; Check your mail servers against 100+ blacklist; Ensure your Web Servers are up and running with valid SSL certificates

The MX lookup is done directly against the domain's authoritative name server, so changes to MX Records should show up instantly. You can click Diagnostics , which will connect to the mail server, verify reverse DNS records, perform a simple Open Relay check and measure response time performance.

This tool requires you to send a test message to MxToolbox. Our systems analyze the headers, the blacklist reputation of your outbound IP address, and your SPF records to generate a comprehensive deliverability report.

Aug 2, 2010 · I have added some additional information to the SMTP Diagnostic test tool so that we can better troubleshoot Server Down alerts when customers are puzzled because they saw no outage. I have added the full SMTP transaction transcripts to the SMTP Diag Alert emails.

This test will lookup an SPF record for the queried domain name, display the SPF Record (if found), and run a series of diagnostic tests (SPF Validation) against the record, highlighting any errors found with the record that could impact email delivery.

Apr 1, 2010 · We wanted to give a bit more insight into the Warning from our SMTP Diagnostic tool about 'Reverse DNS Failing'. When a sending server makes a connection to the recipient server, the recipient server notes the sending IP address and performs a reverse lookup.