Showing results for 
Search instead for 
Did you mean: 

Unable to send emails (POP) when using Plusnet broadband

Posts: 12
Registered: ‎19-05-2016

Unable to send emails (POP) when using Plusnet broadband

Weird one. Suddenly all my devices in the house will not allow me to send email when using Plusnet router. This includes laptop, 3 different mobiles with different Plusnet email addresses and also my tablet. If I change wireless on any device to connect to my mobile broadband router (Three) it sends fine so settings on devices seem to be OK. Anyone any idea? Recently changed to FTTC with new Plusnet Hub 1 router. All has been working fine for a week or so and now this.



Posts: 22,721
Thanks: 9,446
Fixes: 150
Registered: ‎22-08-2007

Re: Unable to send emails (POP) when using Plusnet broadband

POP3 is for receiving emails, this is a SMTP (email sending service) issue.  This rather sounds as though your IP address has been black-balled ... which would be unusual for a Plusnet IP address.

Test SMTP authentication

Email programs often report username / password error for issues not actually related to those being wrong, but for other connectivity issues. Such can be very frustrating when you are convinced that they are correct. Testing SMTP authentication through a command line interface can deliver a more precise error message. The following describes how to do this using TELNET.

This is not difficult, but you need the following resources which might be unfamiliar...

  1. TELNET - this might need installing as an additional option, for Windows see enabling TELNET.
  2. A code64 encoder / decoder such as this.

You can use TELNET to communicate direct with the SMTP server as follows...

Open the code64 encoder in a web browser and leave ready for use in the following steps.

Launch a windows command line window (DOS window) - press windows-key+R - type CMD into the run box - click OK


telnet 587

Press enter. Note if you use one of the other brand email services, use the appropriate SMTP server name for that brand. In response to SMTP server I'm here message, say 'HELLO'...


The SMTP server will then report what it can do after which tell the server you wish to authenticate...

AUTH login

The server should return the following, which is a base64 encoded string that requires your username:

334 VXNlcm5hbWU6

Use the code64 encoder to encode your username and paste it into the telnet window and press enter. For example:


The server should return the following, which is a base64 encoded string that requires your password:

334 UGFzc3dvcmQ6

Paste the base64 encoded password for the username. For example:


The server will then report success or failure, any failure message should clearly indicate the reason for the failure. If the reason for the failure is not clear, please report back the message.

Close the SMTP / TELNET session by entering


The session should look something similar to the below wherein your input is in bold...

220 avasout03 smtp
250-avasout03 hello [your IP address], pleased to meet you
250-SIZE 104857600
250 OK
334 VXNlcm5hbWU6
334 UGFzc3dvcmQ6
235 ... authentication succeeded
221 avasout03 smtp closing connection
Connection to host lost.

Here are some examples of failure responses...

535 ...authentication rejected [as username / password is wrong]
535 ...authentication rejected as source IP has a poor reputation


Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.