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mbogo's avatar
New Contributor

Inability to send e-mail via Thunderbird

After more than five years of successfully using Thunderbird to send and receive e-mail, I have been receiving the following message for the last couple of weeks when trying to send an e-mail:

Sending of the message failed.
The Outgoing server (SMTP) does not seem to support encrypted passwords. If you just set up the account, try changing the 'Authentication method' in 'Account settings | Outgoing server (SMTP)' to 'Normal password'.

Does the Cox SMTP server no longer support encrypted passwords?

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  • DerrickW's avatar
    Valued Contributor

    You should be able to authenticate your password and send email. We do not support the email program Thunderbird, although we can provide the settings you should be using. If it does not function, you would need to speak with Mozilla to troubleshoot the actual program. Here is a link to the server settings you should be using -
  • AllenP's avatar
    Valued Contributor

    Yes it seams like Cox doesn't support encrypted passwords over an ssl/tls connection. Since the entire connection is secure / encrypted, that isn't really a problem. See this thunderbird forum post, it explains it. Just keep ssl/tls on port 465 and select normal password, you should be good to go and you are not compromising security since you are using a secure connection.

  • mbogo's avatar
    New Contributor


    I haven't changed any settings in Thunderbird over the last 5+ years, but suddenly Cox is issuing errors.  This happened in early December too, but righted itself without any action on my part.

    Has Cox dropped support of encrypted passwords when contacting the outgoing SMTP  servers

    Port addresses, etc. were all correct. The link you supplied is not valid but I had checked them previously

  • Tecknowhelp's avatar
    Valued Contributor II

    Cox outsources their email to some unknown vendor in Texas some months ago. Since then, password authentication doesn't work, probably because of a now broken certificate. Since they changed the SMTP server's name( vs it no longer matches the old certificate. 

    DomainTypeClassTTLResponse TimeAnswer
    Answer section: PTR IN 86400 47ms