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Send email via a secured port

Updated 12/15/2016 7:18:12 PM by Comcast Expert


This article applies to Microsoft® Hosted Exchange customers who have not yet been migrated to Microsoft® Office 365. If you are currently using Office 365, please visit Microsoft’s Set up Office 365 for business support page.

To help maintain your company's outgoing email security, follow these instructions to configure your modem.

Send outgoing mail through a secured port on your modem

The Comcast Customer Security Assurance Team recommends configuring your outgoing mail server settings to a secured port. If you use an email client (for example; Outlook, Outlook Express, or Thunderbird) and send through a third-party domain/server (for example, Gmail) using Simple Mail Transfer Protocol (SMTP), you may be unable to send email if a block has been placed on port 25 within your client. If this is the case, you will receive the message shown here:


This can be resolved by configuring the email client to send via alternate port 587 or 465, secured ports that require authentication.

Configure your email client to send email through port 587 or 465


The steps for accessing these settings will differ depending on your email client.

In the Outlook 2007 menu bar, select Tools > Account Settings, highlight the appropriate account, then select Change.

In Outlook 2010, select File > Info > Account Settings, highlight the appropriate account, then select Change.

  1. Step 1:

    Under the Properties tab, select Servers.

  2. Step 2:

    If you are using a third-party domain/server, in the Outgoing mail (SMTP) field, type the webmail server name. If not, skip and go to Step 4.

  3. Step 3:


    Under the Outgoing Mail Server category, check the box for My server requires authentication.

  4. Step 4:

    Select Settings.

  5. Step 5:

    Outgoing mail servers:

    If your outgoing mail server is the same as your incoming mail server, select the radio button for Use same settings as my incoming mail server.


    If you will be using an outgoing mail server that is different from your incoming mail server, select Log on using, and enter the correct Account name (email address) and Password for that account. Select OK.

  6. Step 6:


    On the Advanced tab, enter 587 or 465 in the Outgoing mail (SMTP) field. Select OK.

    Note: Some of these steps will vary depending on the email client in use (for example, in Outlook2007: select Tools > Account Settings, then select the account and click Change).

For additional assistance configuring your modem's port settings, contact the Customer Security Assurance team at 1-877-807-6580.

Outlook 2003/2007 and HMC Webmail users are not impacted if a block is placed on port 25.

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