SUMMARY

Troubleshooting server connectivity and how to test if MailEnable can send to remote servers.

DETAIL

Many ISP's block outbound SMTP traffic to ensure that spammers do not abuse their service. To validate whether mail can be sent to remote hosts, use the telnet utility. This is also useful in checking if mail can be sent from the server, or diagnosing why mail cannot be sent to a remote server.

Instructions follow:

1. From the Windows Start Menu select Start->Run and enter CMD as the application to open. Select OK
2. At the command prompt, enter the following:

telnet mail.mailenable.com 25

The remote mail server should respond with an initiation string similar to the following:

220 mail.mailenable.com ESMTP MailEnable SMTP Service, Version: x-x-x ready at 02/28/19 14:04:45

3. Type the word QUIT and then press enter.

When using the telnet command the server MX record must be used. To find what the MX record is for a domain, use the NSLOOKUP command.  The details for this are below;

1. From the Windows Start Menu select Start->Run and enter CMD as the application to run.

[Then click OK]

2. At the command prompt, enter the following:

nslookup [enter]

>set type=mx

>type domain name your are searching MX record for (e.g. mailenable.com)

A reply like the following should appear:

mailenable.com  MX preference = 10, mail exchanger = mail.mailenable.com

Now it is known what MX record to use for the MailEnable mail server = mail.mailenable.com

Therefore a telnet command for this server will be telnet mail.mailenable.com 25

If this was successful, then no firewall (either local or ISPs) is preventing outbound SMTP traffic. The next step is to try sending an actual message to the remote host. Firstly, determine which remote server to connect to. A domain may have more than one server which is accepting email, and these servers may not match the domain name. The mail servers for a domain are determined by the MX records which have been configured in a DNS. To retrieve the mail server details for a domain, use the nslookup command line utility. For example, to check which servers are accepting email for AOL, enter:

Nslookup –type=mx aol.com

This will return the details of the mail servers, then use these results as the hosts to connect to.

This is outlined as follows:

1. From the Windows Start Menu select Start|Run and enter CMD as the application to run. Then click OK.
2. At the command prompt, enter the following:

telnet mail.mailenable.com 25

The remote mail server should respond with an initiation string much like the following:

220 mail.mailenable.com ESMTP MailEnable SMTP Service, Version: x-x-x ready at 02/28/19 14:04:45

3. Type the following: HELO YourDomainName and then press enter.
The server should reply with something like 250 xxxxxxxx
4. Type the following: MAIL FROM:<senderaddress> where senderaddress is the email address being sent from, and then press enter.
The server should reply with something like 250 xxxxxxxx
5. Type the following: RCPT TO:<recipientaddress> where recipientaddress is the email address being sent to, and then press enter.
The server should reply with something like 250 xxxxxxxx
6. Type the following: DATA and then press enter.
The server should reply with something like 354 xxxxxxxx
7. Enter the text as follows (Note: [CRLF] = Enter Key):
Subject: Test Message[CRLF]
[CRLF].[CRLF]
6. Type the following: QUIT and then press enter.

If this was successful, then MailEnable should be able to send messages to the remote host. If an abnormal response is received for any of the commands that were typed in, then search the MailEnable knowledge base for any articles that may give an indication of the cause of the error.

Example:

C:\>telnet mail.mailenable.com 25
220 mailenable.com ESMTP MailEnable Service, Version: -10.28- ready at 11/20/19 23:49:40
EHLO test.example.com.au
250-mailenable.com [10.1.1.1], this server offers 4 extensions
250-AUTH LOGIN CRAM-MD5
250-SIZE 10120000
250-HELP
250 AUTH=LOGIN
MAIL FROM:<myaddress@mydomain.com>
250 Requested mail action okay, completed
RCPT TO:<theiraddress@theirdomain.com>
250 Requested mail action okay, completed
DATA
354 Start mail input; end with [CRLF].[CRLF]
Subject: Test Message
.
250 Requested mail action okay, completed
QUIT
221 Service closing transmission channel
Connection to host lost.

MORE INFORMATION

Unable to receive mail from remote mail servers: Article ME020239

Troubleshooting Mail Client Connectivity to MailEnable: Article ME020075

Why are messages to external domains not being sent?: Article ME020133

How to troubleshoot SMTP Connectivity issues and Analyse Log Files: Article ME020170