Receiving and sending emails

My email account is with For several hours I have been unable to access or send emails using emClient - I get an error message saying “unauth or invalid email address or password”. However, I can access my account using Talktalk webmail via Google Chrome, but not Firefox.
Talktalk say it is an issue with Mozilla Firefox. I cleared the browsing history which did not work and I have now uninstalled Firefox, but I still have the same problem. Any ideas?

Firefox settings would have no impact on eM Client’s ability to access or send email.  The correct settings for SMTP (outgoing email) is using port 587.  For security policy, use “Force usage of SSL/TLS”.  These settings can be located at menu/tools/accounts and select the SMTP tab.

Thanks for this. I changed the settings as you suggested, but unfortunately I still cannot send or receive emails. I think it may still be an issue for Talktalk, and I am back in touch with them.