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Requirements for Internet Mail Servers sending email to GRU

If You Have A GRU.Net Account But Sometimes Use A Different Internet Service Provider Other Than GRU.Net And Need To Send Mail, Use The New Message Submission Port 587:

In order to help restrict "spam," "worms," etc., many Internet Service Providers (ISPs) including GRU.Net  require that all outbound e-mail on the "default" SMTP port 25 use only our "official" GRU.Net server(s). However, it also severely complicates life for users of mobile/laptop computers, who frequently connect to different networks, requiring changes to their e-mail program configuration with each change of location.

Fortunately, GRU.Net now supports an alternative means of e-mail submission; the Message Submission Port, port number 587. It is specifically designed to be the entry point for new messages, and requires "secure authentication" using TLS. The Message Submission port does not accept messages from unauthenticated sources, helping to protect networks and users from malicious e-mail.
After configuring your e-mail program to send outbound mail via the Message Submission port, you will probably find that you are prompted for your username and password the first time you send a message during each e-mail session. Generally, after you authenticate for the first outbound transmission, your system will remember your credentials as long as you don't exit/quit the program.
The Message Submission Port Essential Facts: 

GRU.Net Outgoing E-mail Host
Message Submission Port 587
Authentication Required? Yes, Username & Password
Connection Encryption TLS (note; SSL is not TLS)

The remainder of this article will show how to configure two common e-mail programs, Microsoft Outlook Express, and Mozilla Thunderbird, to use the Message Submission port. Other e-mail programs will generally be similarly configurable.

How-To: Configuring Outlook Express

You configure Microsoft Outlook Express to use Message Submission port 587 via the following procedure:

  • From the main Outlook Express menubar, select Tools
  • From the Tools dropdown menu, select Accounts...
  • On the Internet Accounts panel, select the Mail tab
  • Highlight the entry for your email account.
  • Click the Properties button
  • In the <your e-mail accountname> Properties dialog box, click the Servers tab
  • In the Outgoing Mail Server section, click the "My server requires authentication" checkbox
  • Click the Settings... button
  • Click the Log on using radiobutton
  • Make sure your username (for the server you use to send mail) is entered in the Account name: field
  • Click the OK button
  • You will be back on the main <your e-mail accountname> Properties dialog box. Click the Advanced tab
  • Set the Outgoing Mail (SMTP): field to 587. SSL is optional, if you wish to use SSL, Click This server requires secure connection (SSL).
  • Click the Apply button
  • Click the OK button
  • Click the Close button
  • If you are using SSL, you must accept the certificate when asked.

How-To: Configuring Thunderbird

You configure Mozilla Thunderbird to use Message Submission port 587 via the following procedure:

  • From the Thunderbird main menu, select Tools
  • From the Tools dropdown menu select Account Settings...
  • In the Account Settings dialog box, from the left-hand pane, select "Outgoing Server (SMTP)". You may have to scroll down in this panel to find this selection, depending on how many accounts you have configured.
  • The Outgoing Server (SMTP) Settings dialog box is shown below.
    1. Enter your preferred outgoing mail server in the Server Name:
    2. Enter "587" as the Port number.
    3. Check the "Use name and password" checkbox
    4. Enter your username for this server in the User Name: field.
    5. Check the TLS radiobutton. SSL is optional, if you would prefer to use SSL, check the SSL radiobutton instead.
  • Click OK.
  • If you are using SSL, you must accept the certificate when asked.

For Further Assistance

If you need additional assistance in configuring your e-mail program, please contact the Support Desk at 352-334-3100 or

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