Drop down the Edit menu, and choose Mail and Newsgroup Account Settings
Click Outgoing Server (SMTP)
On the right hand side next to server name it should say Port: 25
Change that number from 25 to 587
Click OK
Restart Mozilla
Microsoft Outlook and Outlook Express
To change the outgoing mail port from 25 to 587:
In Outlook, drop down the Tools menu
Choose Accounts or Account Options
Click on the Mail tab
Click on Properties
Click on the Advanced tab
Change the outgoing mail from port 25 to port 587
Make sure that the box that says This connections requires a secure connection(SSL) is NOT checked
Click OK
Restart Outlook
Netscape 7.x
To change the outgoing mail port from 25 to 587:
Launch the Netscape mail client
Drop down the Edit menu, and choose Mail and Newsgroup Account Settings
Click Outgoing Server (SMTP)
On the right hand side next to server name it should say Port: 25
Change that number from 25 to 587
Click OK
Restart Netscape
Netscape 4.x
To change the outgoing mail port from 25 to 587:
Launch Netscape
Drop down the Edit menu, and choose Preferences
Expand Mail and Newsgroups by click the + sign
Click Mail Servers
On the right side change the Outgoing Mail Server: from mail.yourdomain.com to mail.yourdomain.com:587
Click OK
Restart Netscape
Eudora for Windows
Eudora has chosen to hide the Port change option in verison 6.0 and up, makeing it more difficult to make this change. If you have purchased Eudora, we would suggest contacting them about makeing this option available by default again. To enable changeing ports:
Navigate to your Eudora install directory.
Look in the Eudora directory for the directory "extrastuff".
In this directory is a file named "esoteric.epi". Drag (copy or move) this file into the main Eudora directory. There will now be options extra listed, including a Ports page.
To change the outgoing mail port from 25 to 587:
Launch Eudora
Drop down the Tools menu, and choose Options
Click on Ports
Change the port from 25 to 587
Click OK
Restart Eudora
Eudora for Mac
As above, Eudora has hidden the ports option in version 6.0 and up. If you have purchased Eudora, we suggesting contacting them about this, as there is no reason to make this difficult. To change the outgoing mail port from 25 to 587:
For version 6.0 and up, quit Eudora and look in the Eudora Application Folder for the folder "Extras". In this folder is a file "Esoteric Settings". Drag this file into the "Eudora Stuff" folder,
Launch Eudora
Drop down the Special menu, and choose Settings
Click on Ports and Protocols
Change the port from 25 to 587
Click OK
Restart Eudora
Entourage
To change the outgoing mail port from 25 to 587:
Launch Entourage
Drop down the Tools menu, and choose Accounts
Click on Mail, and go to Properties
Click Advanced Sending Options
Make sure the box that says "This POP service requires a secure connection" is unchecked
Check the box that says "Override default SMTP port:" and enter in port 25