Why Outlook Can't Access the SMTP Server

Setting up new email accounts in Microsoft Outlook is both straightforward and simple -- that is, as long as the software can obtain the necessary information or you know the connection requirements for your mailbox. If your computer can't send out messages but can still receive them, Outlook can't communicate with the server responsible for delivering emails. Fortunately, fixing connection errors in Outlook requires minimal troubleshooting.

Purpose

Email providers manage messages through an incoming mail server and an outgoing mail server. Microsoft Outlook retrieves mail using the former and sends mail using the latter. When you compose a message and click "Send," the client connects to the outgoing mail server and copies the contents of the message to the server for delivery via simple mail transfer protocol (outgoing mail servers are often referred to as "SMTP servers" for this reason). The provider then relays the message to the appropriate address or addresses.

Setup

In most cases, Outlook detects the address of, and settings for, the outgoing mail server automatically by searching for the necessary information online. For example, Gmail and Yahoo Mail users don't have to configure their mailbox; Outlook can connect to the incoming or outgoing mail server without any user input. The email client, however, may fail to find the server details for less popular providers. If that happens, you must tell Outlook where the server is located along with its connection method.

Conflicts

SMTP uses a default port of 25, but hackers often abuse this port to send spam via mass-mailing worms. As a result, some Internet service providers and Internet security applications restrict communication through port 25. Check with your ISP or review the settings in your security suite to determine if this is the case. If so, contact your mail provider to whether they offer communication through some alternate port, allow port 25 in your firewall or follow the instructions from your ISP to route mail through their outgoing mail server.

Troubleshooting

Email providers, to protect against data theft, usually require mail clients to use a secure connection. If Outlook can't connect using the default settings, click "File," click "Info" and then select "Account Settings" from the Account Information screen. Choose the appropriate mailbox, click the "Change" button and then click "More Settings." Click the "Advanced" tab, and then choose "SSL" from the "Use the Following Type of Encrypted Connection" drop-down menu. Enter "465" into the "Outgoing Server (SMTP)" field, click "OK" and then click "Test Account Settings." If the connection fails, try port 587 instead.