Charter have been blocking outgoing mail for at least the last 10 years that I know of if you connect to the internet using a service not theirs.

There used to be an exception for charter email addresses of using the Outgoing Email Server: mobile.charter.net server name. This is also the recommendation of spectrum. https://www.spectrum.net/support/internet/mobile-email-setup

So I suggest you check your setting in account settings in the outgoing servers(smtp) entry that you are using the correct outgoing server name.

As you suggested, I changed the outgoing server (SMTP) to mobile.charter.net and set it as the default. Unfortunately it did not solve the problem; I got the same error again. Thank you for the suggestion. Janet

I am having this exact same issue. I use Thuderbird, but it also happens to my wife who uses Outlook. I spent nearly an hour with Spectrum support today, and the best I can get out of them is that this is not their error code. <sigh>

I know Spectrum is bad about solving anything other than the most vanilla issues, but if anyone can provide a little more insight that I (we) can use when talking to Spectrum, it would help!

Just to be sure... this is not a problem with my secondary internet provider? Even though I'm hitting Spectrum's server with a non-Spectrum IP address?

And also, clearly this is not a Thunderbird (or Outlook) error, as suggested by Spectrum tech support?

Matt,

From a different thread I found your suggestion to look at the dnschecker.org to see if my IP address was blacklisted... I did, and it is only on one blacklist - dnsbl.spfbl.net.

Is that all it takes to get blocked from Spectrum's server? Is there any way to get OFF the blacklist?

FYI - my IP address is 47.218.251.63, and it is not a Spectrum address (Suddenlink/Optimum).

Duplicate post, see post above

Duplicate post, see post above Apologies if a replay like this shows up multiple times, seems I'm having trouble getting my replies to post...

Latest update...

I just spent about an hour back with Spectrum support. Had to start from the very beginning with the first level phone answerer (guess they can't/don't take notes on cases). Finally got her to transfer me to a "supervisor" - who I don't think is "Level 2 Support", because I know more about email protocols than she does. She INSISTS that this is a problem with Thunderbird, and they don't support Thunderbird. Even though I have the same problem on Outlook, Android mail, and other POP clients.

She says that all they support is the webmail interface. Although, if you go to their tech support website they list all the server configurations for IMAP, and I have been provided server configs for POP. And, POP is working for me at home, and through the cellular network.

I asked if it was at all possible to be transferred to an email expert who could speak intelligently about the issue, and she said she was that expert. Wow. I know that's not true, because I have spoken to more knowledgeable people in the past.

I guess my next move is to try to find another internet provider. They've already lost me as a cable customer, I don't know how they are going to stay in business. I will also be looking for any way to get above her head and complain. Wish me luck with that.

If anyone happens to come across a solution, or a good contact inside Spectrum, please share it!

Duh, another duplicate... Sorry...