There are countless situations in which you might not want to send email via SMTP directly from your site. Maybe you aren’t familiar with PTR’s and A records, or maybe your IP has been blocked / banned via your ISP or some external RBL. If your mail host allows you to use their server as a smart host, you can avoid most of these worries. Up until recently most mail traveled to and from servers and clients using the SMTP protocol which runs on 25 (TCP). Several mail hosts and ISP’s are now requesting or flat out requiring that the mail be submitted to their servers using the more modern mail submission port which is 587 (TCP). For more information on this please see this link. In order to successfully complete this how-to, you must get in touch with your mail host and see which port they want mail submitted on.
I will use port 587 in this example since this is what my mail hosting company requires.
Step 1: Configure Exchange to use the desired port
Open up the Exchange System Manager and expand Servers, Your Server, Protocols, SMTP. Expand SMTP and right click / properties on the Default SMTP Server. Go to the Delivery tab and then click on Outbound Connections. The last box is the port that Exchange is currently configured to send mail on. Once again, for my mail host port 587 is required. Click OK until you get back to main window of Exchange System Manager.
Step 2: Create an SMTP Connector to route mail
Right click on the Connectors folder and choose New -> SMTP Connector. Name the new connector and then choose the option to “Forward all mail through this connector to the following smart hosts.” Now enter in the hostname provided to you by your hosting company. This is usually the same as the outbound mail server that you would configure in your mail client. Under local bridgeheads click add. Select your Exchange server and click OK. Next, select the Address Space tab and click add. Choose SMTP and click OK. Leaving the default email domain of * and the default cost of 1 should be sufficient depending on your Exchange configuration. Click OK after confirming these defaults.
From here we need to configure outbound authentication. Select the advanced tab and click on Outbound Security. Click on “Basic authentication password is sent in clear text” and then click Modify. Enter in the username and password that was given to you by your mail host. Hit OK until you are back down to the main Exchange System Manager window.
Step 3: Verify the configuration
Start by going to start run and typing in services.msc. Locate the Simple Mail Transfer Protocol server and restart it. Now open up Exchange System Manager again and expand Servers, Your server name, Queues. Send a few test email messages from a client machine and watch the queues. If you see domains that were recently sent to showing a ready state all should be well. If you see domains that have a retry status and messages piling up there is an issue somewhere. Go back through all of the settings mentioned above and look for typo’s, misspellings, and other possible obvious points of failure in the configuration. Double check with your mail host and be sure that you are using the correct information.
NOTE: After correcting any issues found, right click on the failed queues and try forcing the connection. It is sometimes necessary to right click each domain and find messages and then delete them.