If you cannot send mail, the problem is likely a restriction by your ISP (Internet Service Provider) as many block the normal sendmail port (25), due to their own security concerns. This can be the case even if sending was working recently as some ISP's roll these changes through without warning.

To give you an idea of how common port 25 blocking is, we've included below links to a few major ISPs and their online documentation regarding port 25 blocking:

For the average user, the easiest way to find out if port 25 is being blocked is to contact your ISP and ask them. For the advanced user, we've included directions below to test port 25 blocking via the command line.

To test if port 25 is blocked, open your command line on your local computer. For windows users, you can access this via start -> run -> cmd. Mac users can use the "terminal" application. Once on the command line, type:

In the above command, please be sure that you replace yourdomain.com with your actual domain name. If you get no response or a failure, port 25 blocking is the likely issue. It is NOT port 25 blocking if you receive a response similar to this:

As your ISP is blocking port 25, the preferred solution is to use the outgoing mail server provided by your ISP. As each Internet Service Proivder has different settings you will need to use (such as username and password, smtp server...), you will need to contact your ISP for the correct settings. We do have alternate solutions to this which involve going over port 465 or 587 instead of 25, however if your ISP begins to block 465 or 587 in the future, you will once again be unable to send email.

Beginning in late March 2010, we are updating many of our servers to run SMTP over port 587 as well as port 25. If your ISP is blocking port 25, simply change your SMTP port number to 587. This setting is usually found in the advanced settings of your email client. Please see the end of this article for more details.

Use the secure, or ssl, port for outgoing mail. This will involve selecting the setting "this server requires a secure connection (ssl)" in your mail program. You only need to make this change for the outgoing mail server. Once you check that box, then change the port listing from 25 to 465 and save the changes. These settigns are usually found in the advanced settings of your email client. Please see the end of this article for more details.

You will also want to change the outgoing server name to secure##.inmotionhosting.com, secure## being the secure alternative of the actual server you are on. For example, if your Welcome Email states that your account is on biz54.inmotionhosting.com, your outgoing server name should be secure54.inmotionhosting.com. If you are unsure, please contact support. This option will work in most cases, however we cannot guarantee that your internet service provider will not some day in the future begin to block port 465.

In most email clients, the SMTP port and SSL settings are updated on the same settings page, and that page is generaly in the advanced settings. The directions below will assist you in finding where to change these settings:

Outlook 2002 and Outlook 2003

Click image for larger view

Start Outlook. On the Tools menu, click E-mail Accounts. Click View or change existing e-mail accounts, and then click Next. Click your account, and then click Change. Click More Settings. Click the Advanced tab.

Outlook 2007

Click image for larger view

Start Outlook. On the Tools menu, click Account Settings. Click to select the target account, and then click Change. Click More Settings. Click the Advanced tab.

Outlook Express 5.x and 6.0

Click image for larger view

Start Outlook Express. On the Tools menu, click Accounts. Click the Mail tab. Click your account, and then click Properties. Click the Advanced tab.

Mac Mail

Click image for larger view

Open Mail. From the Mail menu, choose Preferences. In the Preferences window, click the Accounts button if it is not already selected. In the Accounts list, if you have multiple accounts, click your email account. Click the Server Settings button near the bottom of the pane. If you do not see a Server Settins button, click the drop down list, click "Edit Server List...", and click the "Advanced" tab.

Microsoft Entourage

Click image for larger view

Open Entourage. From the Tools menu, choose Accounts. Click the Mail tab. Double-click the affected account. Click "Click here for advanced sending options."

Thunderbird

Click image for larger view

Open Thunderbird Click the Edit menu, and choose Account Settings Click Outgoing Server (SMTP) On the right hand side click the server to modify and click Edit