Ssl – Secure Email Settings for Email Clients & for PHPMailer

emailSecuritysmtpssltls

I'm trying to work out how to make my outgoing/incoming email's as secure as I can possibly make them.

First of all, my domain has Wildcard OV SSL Certificates, I have copies of the .csr, .crt and .key files but I don't have any PKCS12 files of .p12 or .pfx, is it possible to get these from my SSL certificate so I can digitally sign outgoing emails via email clients like outlook, thunderbird… etc

Secondly, what is currently the "safest" / "best" security settings that I can and should use for my email client(s), below is all of the available options.

Incoming Options

Connection Security:

  • None
  • STARTTLS
  • SSL/TLS (Currently using via port 993)

Authentication Method:

  • Normal Password (Currently using via port 993)
  • Encrypted Password
  • Kerberos / GSSAPI
  • NTLM
  • TLS Certificate
  • OAuth2

Outgoing Options

Connection Security:

  • None
  • STARTTLS
  • SSL/TLS (Currently using via port 465)

Authentication Method:

  • No authentication (Not available)
  • Normal Password (Currently using via port 465)
  • Encrypted Password (Not available)
  • Kerberos / GSSAPI (Not available)
  • NTLM (Not available)
  • OAuth2 (Not available)

Last but not least, the same goes for PHPMailer, should I be using TLS or SSL (what ones better?)

$phpmailer->SMTPSecure = "tls"; // Choose SSL or TLS, if necessary for your server

Best Answer

Try this on how to create p12.

openssl pkcs12 -export -in cert.crt -inkey cert.key -name "Your Name" -out cert.p12

The following are already "safe" and practical for a company to deploy.

  • Incoming Port: POP3 995 or IMAP 993 (SSL/TLS)

    SMTP Authentication Required

  • Outgoing Mail server (SMTP) Port: 465 (SSL/TLS)

    SMTP Authentication Required

Lastly, use TLS whenever you can. TLS performs better and there are security issues with some SSL protocols.

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