Email encryption is here – use STARTTLS everywhere

The site has a link to the starttls everywhere site right at the top - but it's also worth mentioning that the regular 'certbot' client for https everywhere can also be used to create certificates for your own smtpd. The easiest way is just having the sudo ability to temporarily open port 80 for the challenge/response process.

using certbot:

sudo ./certbot-auto certonly -v --standalone --standalone-supported-challenges http-01 -d mail.mydomainname.com

where mail.mydomainname.com is whatever is the full hostname of your MX.

then a pretty typical postfix configuration blob:

# TLS (SSL) private and public keys

# obtained from certbot-auto in /etc/certbot/

# sample CLI to obtain new cert

# sudo ./certbot-auto certonly -v --standalone --standalone-supported-challenges http-01 -d mail.mydomainname.com

smtpd_tls_CAfile=/etc/letsencrypt/live/mail.mydomainname.com/fullchain.pem

smtpd_tls_cert_file=/etc/letsencrypt/live/mail.mydomainname.com/cert.pem

smtpd_tls_key_file=/etc/letsencrypt/live/mail.mydomainname.com/privkey.pem

# TLS (SSL) configuration

smtp_tls_security_level=may

smtp_use_tls=yes

smtpd_use_tls=yes

smtpd_tls_loglevel=1

smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3

smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache

smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for # information on enabling SSL in the smtp client.

That would be fine, too, and reflects in part what MTA-STS is trying to do.

A point that may be obvious, but I would like to make explicit, is that unlike on web, end-users have no good way to express whether they prefer security over deliverability on a connection, which makes downgrade attacks more difficult to deal with. Everyone defaults to preferring deliverablity (falling back to plaintext). In the absence of user intent, it's more important for an email sender to know the recipient mailserver's intent: what level of security should they expect? This can be achieved at varying degrees through DANE, MTA-STS, or a "HSTS Preload List" equivalent for email, but there is currently no reliably deployed standard for this.

(edit: something I forgot to mention: of course, you'd have to trust the initial DNS lookup as well)

Thanks for the plug. The same developer at EFF is working on both STARTTLS Everywhere and Certbot Postfix integration. :-)

(Anyway, the most significant difference between the two is that STARTTLS Everywhere can also enforce certificate validation on recipient sites that request it, which Postfix won't otherwise do.)

This is just not true.

The Internet is full of stories of people having trouble with large email providers (notably Google and Microsoft) accepting self-hosted users' mail. A self-hosted setup's IP starts with 0 reputation (or worse, depending on who owned the IP address beforehand) and will face throttling and outright blocking for a painful amount of time.

Furthermore, if you forward your email to e.g. a Gmail inbox, any spam sent to your address will go towards lowering the reputation of your forwarder, meaning that someone just has to send you a lot of spam to get your forwarder blocked from Google servers.

SPF, DKIM, DMARC and TLS all cannot mitigate the above.

So I support more encryption everywhere, but this is acting like there's something new? I know I've been using STARTLS on SMTP for almost 20 years… Am I missing something?