Kindly refer to the below steps on switching from SMTP port 25 to port 587 in your email client settings.

Microsoft Outlook 2007

1. Open Microsoft Outlook 2007. From the Tools menu select Email Accounts.
2. Select View or change existing e-mail accounts under the E-mail, then click Next button.

3. Select your account, then click Change button.

4. The Internet E-mail Settings dialog box appears, showing the settings for your existing account. Click the More Settings button.

5. Go to Advanced tab, under Outgoing server (SMTP), change port 25 to 587.

6. Click the OK button.

 

Other versions of Microsoft Outlook

1. Tools > Account Settings

2. Double click on your email account > More Settings

3. Goto Advanced tab, under Outgoing server (SMTP), change the port 25 to 587.


Outlook Express

1. Start Outlook Express, click the Tools menu at the top of the window and then click Accounts.

2. Double click on your email account

3. Goto Advanced tab, under Outgoing server (SMTP), change the port 25 to 587.


Mozilla 1.x

1. Launch the Mozilla mail client.

2. Drop down the Edit menu, and choose Mail and Newsgroup Account Settings.

3. Click Outgoing Server(SMTP).

4. On the right hand side next to the server name change the port 25 to 587.


Netscape 7.x

1. Launch the Netscape mail client.

2. Drop down the Edit menu, and choose Mail and Newsgroup Account Settings.

3. Click Outgoing Server(SMTP).

4. On the right hand side next to server name change the port 25 to 587.

Netscape 4.x

1. Launch Netscape.

2. Drop down the Edit menu, and choose Preferences.

3. Expand Mail and Newsgroups by click the + sign.

4. Click Mail Servers.

5. On the right side change the Outgoing Mail Server: from mail.domain.com to mail.domain.com:587.