Overview

Note : This solution requires the SMTP Servers connection information This information would be the IP Address or DNS Hostname of the Mail server, the Port number used to connect, as well as an Email account on the server Also note that if any Encryption or SMTP Authentication is used on the server, the steps may not work entirely, but can be used to verify connectivity and online status of the mail server. Note : The steps to Perform a Telnet Test depending upon the Operating System used.  Perform a Telnet Test on a Windows 7, 8 or 10 PC :   Perform a Telnet Test on a Apple macOS 10.7.x to 10.12.x : Note : Telnet support has been removed from MacOS 10.13 High Sierra and later releases. Open the  Start Menu . Type  Control Panel  into the  Search  Field. Select the  Control Panel . Go to  Large Icons  or  Small Icons  under Catagory View. Select  Programs and Features . Select  Turn Windows Features On or Off . Check the Box marked  Telnet Client Select OK. Close the Programs and Features window. Open the  Start Menu . Type  CMD  into the Search Box. Select  CMD.exe  or  Command Prompt . Type  TELNET  and press Enter. Note : Type the following commands carefully as the backspace key is interpreted as a character by the Telnet Client software. Type the command  open  and press Enter (ie:  open smtp.gmail.com 25 ) Note : If connection to the SMTP server is successful, you will receive a reply similar to ' 220 ESMTP Server '. Type  elho   and press Enter (ie:  ehlo gmail.com ) Use the command  helo    instead, if the server returns an error with the ehlo command. Note : The server may require a username and password if SMTP Authentication is enabled In most cases, the email address is the username, and password is the password of the email account on the mail server. Type  mail from:  and press Enter. Note : A response similar to  250 Sender OK  means the command was successful. Type  rcpt to:  and press Enter. Note : A response similar to  250 OK - Recipient  means the command was successful. Type  data  and press Enter. Note : A response similar to  354 Send Data  means the command was successful. Type  subject:  and press Enter (ie:  subject:Test ) Enter the message text for the Email to be sent. Type a  single period (.) on a blank line  followed by pressing Enter to end the message (ie: ) Note : A response similar to  250 Queued mail for deliver  means the command was successful. Type  quit  and press Enter to disconnect from the Mail Server. Open  Finder . Select  Applications . Select  Utilities . Select  Terminal . Note : Type the following commands carefully as the backspace key is interpreted as a character by the Telnet Client software. Type  Telnet  and press the Return key (ie:  Telnet smtp.gmail.com 25 ) Note : If connection to the SMTP server is successful, you will receive a reply similar to ' 220 ESMTP Server '. Type  elho   and press Enter (ie:  ehlo gmail.com ) Use the command  helo    instead, if the server returns an error with the ehlo command. Note : The server may require a username and password if SMTP Authentication is enabled In most cases, the email address is the username, and password is the password of the email account on the mail server. Type  mail from:  and press Enter. Note : A response similar to  250 Sender OK  means the command was successful. Type  rcpt to:  and press Enter. Note : A response similar to  250 OK - Recipient  means the command was successful. Type  data  and press Enter. Note : A response similar to  354 Send Data  means the command was successful. Type  subject:  and press Enter (ie:  subject:Test ) Enter the message text for the Email to be sent. Type a  single period (.) on a blank line  followed by pressing Enter to end the message (ie: ) Note : A response similar to  250 Queued mail for deliver  means the command was successful. Type  quit  and press Enter to disconnect from the Mail Server.