Can receive but not send emails..

[#1]

Hi,

Using Microsoft® Outlook® 2019 MSO (Version 2410 Build 16.0.18129.20158) 32-bit on Win10 PC I can receive but am unable to send emails. Outlook states 'Task 'brian@b*************.co.uk - Sending' reported error (0x800CCC0F) : 'The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).'

Been fine until today. Not changed any settings which are as attached. Have tried with and without Nordvpn. Any suggestions appreciated..

[#2]

Meanwhile..I am trying to follow @Townman advice on a post 1/4/24 Test SMTP authentication and fell at first hurdle. I entered '

telnet relay.plus.net 465

After 30 seconds it says ' C:\Users\PC>'  Any suggestions welcome..

[#3]

Try : telnet relay.plus.net 587

[#4]

For the command above, try these instructions

telnet relay.plus.net 587

after a slight pause the server should respond

220 avasout-ptp-002 smtp relay.plus.net

then enter this command

EHLO relay

the server should respond

250-avasout-ptp-002 hello [your public IP Address], pleased to meet you

If I recall you will not receive this response for a blacklisted IP Address

CTRL +]  followed by quit to leave telnet back to  terminal application.

I thought it's preferred to use "SMTP: relay.plus.net port 587 encryption STARTTLS"

[#5]

The instructions state port 587 not 465.

Port 465 is obsolete and requires an encrypted connection.

[#6]

Thank you for your help and suggestions.

So far I have got this far..

220 avasout-ptp-003 smtp relay.plus.net
ehlo relay
250-avasout-ptp-003 hello [217.146.93.245], 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
VlhObGNtNWhiV1U2
334 UGFzc3dvcmQ6
VUdGemMzZHZjbVE2
535 ...authentication rejected

Not sure about the code 64 encoder part. I assume to use the code64 encoder to encode my username I paste VXNlcm5hbWU6 in to the top part 'base 64 format' press 'encode' and copy and paste the answer in to DOS window? I haven't altered 'destination character set' or 'destination newline separator'

[#7]

That simply means that the username / password was rejected, with the credentials provided.  Did you use the most simplistic of user ID options - your accountname (or accountname+mailboxname)?

Can you login to Webmail AND send successfully?

Is this is legacy email account - that is one not associated with a current paid for broadband service?

In the past we have seen an issue where following a change of a password on a legacy email account it became impossible to send email.  It took a deal of negotiating by the SUs to have that recognised as "incorrect".  Therefore it is worthwhile eliminating that scenario being applicable here.

[#8]

I assume to use the code64 encoder to encode my username I paste VXNlcm5hbWU6 in to the top part 'base 64 format' press 'encode'

@BrianD1 No, at the '334 VXNlcm5hbWU6' prompt you paste your Plusnet account name into the encoder and paste the encoded value into the DOS window. Similary at the '334 UGFzc3dvcmQ6' prompt you encode your password and paste that into the DOS window

[#9]

@MisterW 

You beat me to it!!

Being fearful that @BrianD1 might have inadvertently disclosed their username and password, I was running the above diagnostic through the Base 64 decoder ... and realised that they had put the returned prompts into the encoder...

• VlhObGNtNWhiV1U2 - > VXNlcm5hbWU6 -> Username:
• VUdGemMzZHZjbVE2 -> UGFzc3dvcmQ6 -> UGFzc3dvcmQ6

@BrianD1 

When posting these diagnostics DO NOT post the encoded strings you entered.

You should ignore my previous post, unless you find that you cannot SEND emails using webmail.

[#10]

OK so I now have the following..

220 avasout-peh-002 smtp relay.plus.net
ehlo relay.plus.net
250-avasout-peh-002 hello [185.158.242.152], pleased to meet you
250-HELP
250-AUTH LOGIN PLAIN
250-SIZE 104857600
250-PIPELINING
250-8BITMIME
250-STARTTLS
250 OK
AUTH login
334 qweqweqq
qwqwqwq
334 qwqweqqwe
qweqweqwe
235 ... authentication succeeded
quit

Just to confirm I can send emails by webmail..

[#11]

@BrianD1 

Good so you have confirmed that there is no impediment in accessing the SMTP server, so nothing wrong on the Plusnet side, thus the issue much be with the Outlook client.

There are a lot of references to the reported error code (try Googling it) some of which cite the version of TLS, which given the age of your your software might be relevant.  See

• error (0x800CCC0F) - Microsoft Community
• Problems enforcing TLS on newer Outlook versions; security of STARTTLS - Microsoft Q&A

Try setting the SMTP server to relay.plus.net with (each in turn)

1. Port 587 NO ENCRYPTION
2. Port 587 STARTTLS
3. Port 465 SSL/TLS

If (1) works but (2) does not, that would suggest an issue with TLS version support on your laptop / OL 2019

(3) use only in desperation - it is an obsolete interface.

Remember the SMTP server setting should be configured as "My server requires authentication (a logon)".

[#12]

I've just checked again and my emails have been sent! I have no idea if what I did before did this or plusnet have changed something but thank you @Townman , @MisterW @Dan_the_Van @Champnet for your patience and help!

[#13]

I would suspect some muddle over the server settings / a fumble with the credentials.  I've spent hours with the same trip points, especially when using the email address rather than the account name as the logon ID.  There more there is to type, the greater the risk of there being a mistake ... and the difference between "." and "," in the form field is easy not to see.

Good luck.

[#14]

Thank you @Townman . I have set the SMTP server to relay.plus.net with Port 587 STARTTLS and all is well! Thank you again..