There are a few reasons why changing your outgoing port number is a necessary step in troubleshooting. You may find that your mail client has not been sending since you initially set it up, or you may find it has been sending for quite some time and you now see errors.

Common symptoms of needing an outgoing port number changed:

• You can still receive mail but an error pops up when you send messages. You verify the outgoing server name is typed correctly. The error may say that the software is unable to connect to your outgoing server and to contact your service administrator or Internet service provider.
• Your messages are starting to gather in the outbox but you are not getting any noticeable errors.

In both scenarios the cause can be that the outgoing port number is incorrect or being blocked.  There are many ISPs that are now blocking the default outgoing port that many mail clients set up automatically. (Port 25) They do this to protect users from spam and viruses that direct infected machines to send through the default ports.  Typically changing the port to either 2525 or 587 will resolve the issue.

Your internal virus scanning system or firewall may do the same out of taking an action to protect the machine.

Whether you may be troubleshooting your mail client or setting it up for the first time, these instructions will walk you through an important part of making sure you are successfully sending mail.

Instructions for individual Mail Clients:

Microsoft Outlook® Express

Microsoft Outlook® 2003

Microsoft Outlook® 2007

Microsoft Outlook® 2010

Windows® Live Mail

Mac Mail for OSX® 10.3 Panther and Mac Mail OSX® 10.4 Tiger

Mac Mail for OSX® 10.5 Leopard

Microsft Outlook® for Mac 2011

Entourage®

Thunderbird®

iPhone®, iPad®, iPod®

Droid®

Microsoft Outlook® Express

• From the Tools menu click the option for Accounts
• From the Internet Accounts screen, choose the Mail tab and select the account you wish to edit by double clicking the account or highlighting it and selecting Properties on the right.
• On the Advanced tab you will find the section for Outgoing mail (SMTP) port number. If this says 25, remove and type in the alternate port 2525 or 587. You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending. 

Microsoft Outlook® 2003

• From the Tools menu choose the option for E-mail Accounts.
• From the Email Accounts screen, choose the option to View or change existing e-mail accounts and press Next.
• Select the account you wish to edit by double clicking the account or highlighting it and selecting Change on the right.
• From the bottom right of the Internet E-mail Settings page select More Settings.
• From the More Settings page choose the Advanced tab.
• On the Advanced tab you will find the section for Outgoing server (SMTP) port number.
• If this says 25, remove and type in the alternate port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

Microsoft Outlook® 2007

• From the Tools menu choose the option for Account Settings.
• From the E-mail accounts screen, choose the E-mail tab.
• Select the account you wish to edit by double clicking the account or highlighting it and selecting Change
• From the bottom right of the Internet E-mail Settings page select More Settings.
• On the Advanced tab you will find the section for Outgoing server (SMTP) port number.
• If this says 25, remove and type in the alternate port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

Microsoft Outlook® 2010

• From the File menu choose Account Settings.
• Select the account you wish to edit by double clicking the account or highlighting it and selecting Change
• From the bottom right of the Internet E-mail Settings page select More Settings.
• On the Advanced tab you will find the section for Outgoing server (SMTP) port number.
• If this says 25, remove and type in the alternate port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

Windows® Live Mail

• From the Tools menu click the option for Accounts
• From the Internet Accounts screen, select the account under Mail you wish to edit by double clicking the account or highlighting it and selecting Properties on the right.
• On the Advanced tab you will find the section for Outgoing mail (SMTP) port number.
• If this says 25, remove and type in the alternate port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

Mac Mail for OSX® 10.3 Panther and Mac Mail OSX® 10.4 Tiger

• From the Mail tab select the option for Preferences.
• Select the e-mail account you wish to edit by clicking on the account listed on the left menu.
• From the Account Information screen you will see the last option on the bottom of this page is Outgoing Mail Sever (SMTP)
• Select the option for Server settings.
• If the Server port says 25, remove and type in the alternate port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

 Mac Mail for OSX® 10.5 Leopard

• From the Mail tab select the option for Preferences.
• Select the e-mail account you wish to edit by clicking on the account listed on the left menu.
• From the Account Information screen you will see the last option on the bottom of this page is Outgoing Mail Sever (SMTP)
• Choose the drop down arrow next to the server name and press to option to Edit Server List.
• If multiple accounts exist, select the server you wish to edit.
• Under the Account Information section, if Use default ports is selected, select the option for Use custom port and type in 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

Microsft Outlook® 2011 for Mac

• From the tools menu select the option for Accounts.
• Select the e-mail account you wish to edit by clicking on the account listed on the left menu.
• At the bottom of the account details you will see the Outgoing server and port number field.
• Select to Override default port and type in 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

 Entourage®

• From the tools menu select Accounts at the bottom.
• From the Mail tab, select the account you wish to edit by double clicking the account or highlighting it and pressing Edit.
• From the Account Settings tab, navigate to the bottom under Sending mail - SMTP server.
• You will select the option that states “Click here for advanced sending options”
• Select the option to Override default SMTP port and type in 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

 Thunderbird®

• From the tools menu select the option for Account Settings.
• From the left side menu choose the account you wish to edit.
• Select the option on the left for Outgoing Server (SMTP) and select the SMTP server you wish to edit.
• After pressing Edit a new box will pop up with advanced settings.
• If the Port is set to 25, remove and type in the alternate port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

iPhone®, iPad®, iPod®

• From your home screen choose the option for Settings
• From the Settings screen, choose the option for Mail, Contacts, and Calendars.
• Choose the account you wish to edit by tapping that account.
• Scroll to the bottom of the next screen and under Outgoing Mail Server select the option for SMTP.
• Select the Primary Server which should say On.
• On the next screen you will see the option for Server Port at the bottom.
• If the Port is set to 25, remove and type in the alternate port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

Droid®

Due to the different versions of Android and the many mail clients that can be used on those devices; this is an example of just one of those clients. Please contact your provider if you need assistance in finding the location of this advanced setting

• Access your mail application and choose the option (typically a Menu button) where you will be able to see more settings.
• From the settings screen you will want to choose Account settings.
• When you choose to edit the account, click Next until you see the screen for Outgoing server settings.
• If the port number is not correct, remove and type in the port 2525 or 587.  You are free to use either 2525 or 587 and may need to try both of them before you are successfully sending.

Related Articles

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How to Enable SMTP Authentication

Troubleshooting Sending Errors