Outgoing emails not working from other networks

[comiconor]

I use outlook 365 connected to a legacy NTLWorld address.

It has all the correct Incoming and outgoing settings, along with the app password used for authentication. 

I also have the mail setup in client.

All works fine when connected to my Virgin media fibre. However once connected to another network, outgoing mail will not send. It stays in the outbox.

This happens on multiple devices.

I can only assume it's blocking non-virgin connections from sending mail?

[coenoby]

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@comiconor wrote:

I can only assume it's blocking non-virgin connections from sending mail?

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Virgin Media do sometimes block outgoing emails sent from email apps and clients on your VM home network. That is usually because your IP address is on a blocklist because there is evidence of malware on a smart device on your home network.

To troubleshoot the cause I would suggest using the Curl command in Windows to see what error the VM SMTP server is reporting. Sadly email apps and clients do not pass that error message on.

To use Curl:

1) Copy the following line of command text and then paste it into a MS Word document (or which ever text editor you prefer) so that you can edit it.
curl -v smtps://smtp.virginmedia.com -u username:password

2) Once you have pasted it into Word, replace "username" with your full Virgin Media email address, and "password" with your mail app password. So that part should now say something like richardbranson@ntlworld.com:dub-plan-trick-bank It is important to keep the colon : and the space before and after that string of text exactly as per the original line of text in step 1.

3) Type cmd into the Windows 10 / 11Search bar, press Enter and then Open the Command Prompt app.

4) Copy the full line of text that you just amended in step 2 from the Word document and paste it where the cursor is blinking in the Command Prompt. Then press Enter.

After a second or two you should then see a long string of output that either ends with a line which says something like:

"Connection #0 to host smtp.virginmedia.com left intact" in which case there is no error being reported by VM

Or
< 535 5.7.8 Authentication Credentials Invalid (VMnnn)  in which case the connection has failed and the VM 3 digit error code gives an indication of the reason for that failure.
It is that error line, particularly the "VMnnn" code that we need you to give us please but do not post the full output from the curl command.

As a temporary work around, you should still be able to send emails:

• using VM's webmail service or
• from your email clients by using a VPN instead your VM wifi. (The VPN will provide you with a new IP address that should not be blocked by VM.)

Sorry to go on at such length but the VMnnn error code would be a great help in enabling a forum member to advise you how to get the problem resolved.

Coenoby