This article troubleshoots e-mail not sending using 3 Mobile Broadband and shows you how to fix the issue by using SMTP over port 587. Applies to our Ecenica Email Hosting, Roaming SMTP and SMTP for iPhone services.


Email will not send using your SMTP server when connected to 3 Mobile Broadband.

Your email application such as Outlook, Mail, Thunderbird, or iPhone may timeout when sending or return the following error;

SMTP 554 Transact Failed – Transaction failed; Port 25 error; The connection to the server has failed- Error Number: 0x800CCC0E


3 restricts access to SMTP email on port 25.


If you’ve upgraded to Ecenica Roaming SMTP or subscribe to Ecenica SMTP for iPhone, you can configure your email application to access the SMTP server on port 587.

Changing to port 587 tells your email application to connect to our SMTP servers using a different route and bypasses Three’s restrictions.

If you use your ISP to send email then you’ll need to contact your ISP for assistance. Changing the ports may still work, but you’re best asking them first if they support SMTP over port 587.

Using port 587 but still can’t send?

If you’ve updated to port 587 or are already using port 587 and still can’t send email, please consider the following;

  • Double-check your SMTP settings.
  • Some mail apps require restarting for changes to come into affect.
  • Check your firewall is allowing access over port 587.
  • Many ISP’s limit access to their SMTP to ensure you only use it for home use. If you’re trying to use your ISP’s SMTP service and ask your ISP is they support SMTP over port 587.

My ISP only supports SMTP on port 25. What now?

Why not consider our Roaming SMTP service. Ecenica Roaming SMTP gives you a flexible, dependable and secure SMTP service that you can rely on. Use at home, work or on the move. For a low fee, you can send email from any location, computer or phone – including iPhone. See How can I order Roaming SMTP?

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