Please check the free script written by the firm where one of the highly qualified folks at Security SE works: https://labs.portcullis.co.uk/tools/ssl-cipher-suite-enum/

ssl-cipher-suite-enum identifies the following common security issues relating to SSL: ...Support of key exchange algorithms that don’t support forward secrecy – or equivalently, cipher suites that allow sniffed traffic to be retrospectively decrypted if the private SSL key were to be compromised.

If you want to do it slowly and by hand, `openssl`

portmanteau toolset is very handy:

From https://community.qualys.com/thread/12193:

`openssl s_client -starttls smtp -crlf -connect YOUR_SMTP_SERVER:25`

If you see DHE (Diffie-Hellmann Ephemeral) in the cipher suite, it's PFS.

From this post at Security SE
```
TLS_DHE_DSS_WITH_DES_CBC_SHA DHE-DSS-CBC-SHA
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA DHE-DSS-DES-CBC3-SHA
TLS_DHE_RSA_WITH_DES_CBC_SHA DHE-RSA-DES-CBC-SHA
TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA DHE-RSA-DES-CBC3-SHA
```

```
TLS_DHE_DSS_WITH_AES_128_CBC_SHA DHE-DSS-AES128-SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA DHE-DSS-AES256-SHA
TLS_DHE_RSA_WITH_AES_128_CBC_SHA DHE-RSA-AES128-SHA
TLS_DHE_RSA_WITH_AES_256_CBC_SHA DHE-RSA-AES256-SHA
TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA DHE-DSS-CAMELLIA128-SHA
TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA DHE-DSS-CAMELLIA256-SHA
TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA DHE-RSA-CAMELLIA128-SHA
TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA DHE-RSA-CAMELLIA256-SHA
TLS_DHE_DSS_WITH_SEED_CBC_SHA DHE-DSS-SEED-SHA
TLS_DHE_RSA_WITH_SEED_CBC_SHA DHE-RSA-SEED-SHA
```

If we include the Elliptic Curve ciphers, the following also implement PFS:

```
TLS_ECDHE_RSA_WITH_NULL_SHA ECDHE-RSA-NULL-SHA
TLS_ECDHE_RSA_WITH_RC4_128_SHA ECDHE-RSA-RC4-SHA
TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA ECDHE-RSA-DES-CBC3-SHA
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA ECDHE-RSA-AES128-SHA
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA ECDHE-RSA-AES256-SHA
TLS_ECDHE_ECDSA_WITH_NULL_SHA ECDHE-ECDSA-NULL-SHA
TLS_ECDHE_ECDSA_WITH_RC4_128_SHA ECDHE-ECDSA-RC4-SHA
TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA ECDHE-ECDSA-DES-CBC3-SHA
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA ECDHE-ECDSA-AES128-SHA
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA ECDHE-ECDSA-AES256-SHA
```

If you also want to include TLS 1.2 (note that there are no TLS 1.1 specific suites) then you can expand the list to include:

```
TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 DHE-RSA-AES128-SHA256
TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 DHE-RSA-AES256-SHA256
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 DHE-RSA-AES128-GCM-SHA256
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 DHE-RSA-AES256-GCM-SHA384
TLS_DHE_DSS_WITH_AES_128_CBC_SHA256 DHE-DSS-AES128-SHA256
TLS_DHE_DSS_WITH_AES_256_CBC_SHA256 DHE-DSS-AES256-SHA256
TLS_DHE_DSS_WITH_AES_128_GCM_SHA256 DHE-DSS-AES128-GCM-SHA256
TLS_DHE_DSS_WITH_AES_256_GCM_SHA384 DHE-DSS-AES256-GCM-SHA384
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 ECDHE-RSA-AES128-SHA256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 ECDHE-RSA-AES256-SHA384
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 ECDHE-RSA-AES128-GCM-SHA256
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 ECDHE-RSA-AES256-GCM-SHA384
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 ECDHE-ECDSA-AES128-SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 ECDHE-ECDSA-AES256-SHA384
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 ECDHE-ECDSA-AES128-GCM-SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 ECDHE-ECDSA-AES256-GCM-SHA384
TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_CBC_SHA256 ECDHE-ECDSA-CAMELLIA128-SHA256
TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_CBC_SHA384 ECDHE-ECDSA-CAMELLIA256-SHA384
TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 ECDHE-RSA-CAMELLIA128-SHA256
TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384 ECDHE-RSA-CAMELLIA256-SHA384
```