Which Port to use (iprimus email address, Starlink Internet, Microsoft Outlook)

Copper Contributor

Hi there, I have an iprimus email I am trying to use & recently just got Starlink Internet. I am using Microsoft outlook on Windows Pc. It wont allow my outgoing mail to send using Port 25 so I changed to 587 port. It shows me all emails have been sent, yet they are not being received at the other end??? I can receive email fine using Port 110. Can anyone suggest what I am doing wrong? Cant get onto Support at Starlink, Microsoft said its up to iprimus server settings, Yet iprimus say to use Port 25?

3 Replies

@kysa351I have found exactly the same issue and sadly I see you have no replies.  Have you managed to find a solution and are willing to share ? 


It is possible that your ISP (Starlink Internet) is blocking outgoing connections on port 25, which is commonly used for sending email, to prevent spam. This is a common practice among ISPs to prevent spam and other email-related security issues.

In such cases, using an alternative port like 587 is recommended, as you have already tried. However, some email servers may require a specific port to be used for outgoing email. In the case of Iprimus, they may require port 25 to be used for outgoing email.

To troubleshoot the issue, you can try the following:

  1. Double-check your email settings in Microsoft Outlook to ensure that you have entered the correct email address, username, password, and server settings.

  2. Try using a different email client, such as Thunderbird, to see if the issue persists. This can help identify if the problem is with Microsoft Outlook or the email server.

  3. Try different port numbers for outgoing email, such as 465 (SSL/TLS), 2525, or 587 (TLS), to see if any of these work.

  4. Contact your email service provider (Iprimus) and ask them for the correct port number to use for outgoing email. They may also be able to provide additional support to help you resolve the issue.


I hope this helps!


@Mark_Albin @kysa351 

Thank you so much for taking the time to make the suggestions.  I had a very frustrating few days trying to work through the problem.  I returned to my testing this morning and found that it now works, in so much that when I send an email from the Outlook client, not only do the emails say they are sent but they also reach the recipient !  I was contacted by iPrimus tech support who made some suggestions to do with the outgoing server details but they were unable to resolve the issue - in fairness to them though, because I was able to successfully send the emails when NOT using Starlink, there was little they could do.  I am still waiting on a response from Starlink support !!


There is an important piece of information missing from iPrimus's detail on server setup, in that most ISPs block port 25 !  What they don't advertise is that port 587 should be used as an alternative.  Starlink definitely block port 25.  Telstra's Bigpond service (my previous ISP) also blocked port 25 a few years ago so my setup always was 587.


So my issue is now resolved and emails are sending reliably again.  Unfortunately I have no idea why they stopped and now that Starlink see my issue has passed, they may never advise !  Also worthy of note is that I was using the options for delivery receipt to try and assess whether emails were getting to the destination server.  Now that I have it working again its pretty obvious they were not working anyway !