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This is usually in the support section of their website searching for "mail settings" or "SMTP" will usually find it. Look for an SMTP mail settings article on the mail provider's site.Check that the settings are the same as documented in the article for your mail provider ( Gmail, Yahoo, Comcast, Hotmail, Sympatico) OR In the Thunderbird menu bar, click the Tools Edit menu and select Account Settings, or click the Application menu button and select Options Preferences and Account Settings from the sub-menu, and select Outgoing Server (SMTP) from the bottom of the list in the left panel.Verify that your mail server supports the minimum version of TLS.Verify that your outgoing email is not being blocked.If your existing configuration suddenly stopped working after updating to Thunderbird 78, it might be your Antivirus or Firewall blocking the new version, or your email provider using outdated TLS security protocols. The problem suddenly started after updating to Thunderbird version 78?
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