When using mutt on my Mac, I use msmtp to continue the alliteration as an SMTP agent, to send mail through an actual authenticated SMTP server versus trying to connect from my laptop, which not many mailservers will accept.

I’m either missing something, or it’s a real pain with keys when using TLS, especially on the Mac, where the CA certs aren’t present except in the Keychain. I found some guides to getting this working with Gmail, but not Rackspace’s email service.

This is the .msmtprc file I ended up using:

account default
port 587
tls on
tls_starttls on
tls_fingerprint CD:E1:CD:60:FC:8C:8F:3B:6F:17:62:70:61:51:75:3D
auth on
host smtp.emailsrvr.com
user "you@example.com"
password "maybe you do not want it here"

Don’t trust me on the tls_fingerprint line. (I’m not up to anything, but you don’t know that.)

This page documents their SMTP settings, including the hostname. It doesn’t give you TLS fingerprints or a CA cert file, because no one on the Internet does that.

Following this advice concerning Gmail, I adapted it to find the fingerprint for Rackspace:

echo -n | openssl s_client -connect smtp.emailsrvr.com:587 \
 -starttls smtp -showcerts > x.tmp

That will save the exchange, which includes the key. You could probably extract it from there, but it was easier for me to go on and just get the fingerprint:

openssl x509 -noout -fingerprint -md5 -in x.tmp

Take the bit after MD5 Fingerprint= and drop that into .msmtprc on the tls_fingerprint line.

There’s got to be an easier way…