Many ISPs are now blocking port 25. If you are unable to send email but are able to receive, you may need to change your outgoing SMTP server port to 26.
Here are the related instructions for the most popular email clients:
Thunderbird
To change the outgoing mail port from 25 to 26:
Launch the Thunderbird mail client
Drop down the Edit menu, and choose Account Settings
Click Outgoing Server (SMTP)
On the right hand side select the server to modify and click Edit
Change the port number from 25 to 26
Click OK
Restart Thunderbird
Microsoft Outlook and Outlook Express
To change the outgoing mail port from 25 to 26:
In Outlook, drop down the Tools menu
Choose Accounts or Email Accounts
View or change existing e-mail accounts should be marked
Click Next
Select the account and click Change
Select More Settings
In Outlook Express, drop down the Tools menu
Choose Accounts
Select the account and click Properties
Click on the Advanced tab
Change the outgoing mail from port 25 to port 26
Make sure that the box that says This connections requires a secure connection(SSL) is NOT checked
Click OK
Restart Outlook
Mac Mail 10.5+
To change the outgoing mail port from 25 to 26:
Launch Mac Mail
Drop down the mail menu, and choose preferences
Select the email account to modify under accounts .
Beneath Outgoing server (SMTP) click on the drop down bar and select "Edit SMTP server list...".
Click on your desired Outgoing server and then click advanced.
Select option for custom port and type in 26.
Click OK
Restart Mac Mail
Eudora for Windows
Eudora has chosen to hide the Port change option in version 6.0 and up, making it more difficult to make this change. If you have purchased Eudora, we would suggest contacting them about making this option available by default again. To enable changing 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 26:
Launch Eudora
Drop down the Tools menu, and choose Options
Click on Ports
Change the port from 25 to 26
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 26:
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 26
Click OK
Restart Eudora
Entourage
To change the outgoing mail port from 25 to 26:
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 26
Click OK
Restart Entourage
@Thulashi
