Outgoing emails - unable to send

SGM — Fri, 21 Feb 2025 17:53:55 GMT

Hi, wondering if anyone could point me to a resolution.(I’m not particularly technical so bear with me.)

We have a plus net legacy email account we use with two secondary email accounts off it. It has in past few days stopped sending outgoing emails from any of the three accounts, citing ‘user or password incorrect’ or authentication error. The accounts receive incoming mails.

The devices we use are a windows pc, two iPhones, two iPads, and an android mobile. All were okay sending and receiving up to a few days ago.

Due to the password error I changed / reset, via plus net, the main account password and then the two sub accounts passwords. Still no luck. (I must admit I have been going around in circles now with the different devices and trying to work out if I have amended to the new passwords.)

The accounts work via webmail, both sending and receiving.!

Any advice (or further information required) to resolve it please.

Many thanks in advance.

Re: Outgoing emails - unable to send

Townman — Fri, 21 Feb 2025 18:20:08 GMT

@SGM wrote:

We have a plus net legacy email account we use with two secondary email accounts off it. It has in past few days stopped sending outgoing emails from any of the three accounts, citing ‘user or password incorrect’ or authentication error. The accounts receive incoming mails.

So are you connecting over a Plusnet broadband service?

This has all the hallmarks of connecting over a third party internet connection using an IP address with a poor reputation. Did the point of now not working, coincide with the router restarting?

Few email clients provide clarity over why a connection is refused - they just report "password error" for everything. You need a more detailed view of the issue and that requires a diagnostic test...

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...

TELNET - this might need installing as an additional option, for Windows see enabling TELNET.
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

Enter...

telnet relay.plus.net 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'...

EHLO relay.plus.net

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:

bXl1c2VybmFtZQ==

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:

bXlwYXNzd29yZA==

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

quit

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

220 avasout03 smtp relay.plus.net
EHLO relay.plus.net
250-avasout03 hello [your IP address], pleased to meet you
250-HELP
250-AUTH LOGIN PLAIN
250-SIZE 104857600
250-PIPELINING
250-8BITMIME
250-STARTTLS
250 OK
AUTH LOGIN
334 VXNlcm5hbWU6
bXl1c2VybmFtZQ==
334 UGFzc3dvcmQ6
bXlwYXNzd29yZA==
235 ... authentication succeeded
quit
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
535 Too many SMTP auth failures. Please try again later.

If you get "Source IP has a poor reputation" try finding out your current IP address, turn the router off for 2 hours then try again, checking to see if you have a different IP address.

Google "Whatsmyipaddress".

Re: Outgoing emails - unable to send

SGM — Mon, 24 Feb 2025 12:17:56 GMT

Many thanks for your input Townman.

From what you said, i presumed there was a chance it was connectivity through my router which is gigaclear fibre. Your detailed checking procedure seemed a bit technical for me, sorry! Anyway so I tried emails via mobile data (Which I know is a basic but I hadn’t done it) , they sent and received. Thus more than likely router issue. Turned it off overnight and, voila, it all worked again next morning. Thanks for your input and directing me.

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