Add a space to the password writing so it hopefully doesn't go to
shell history.

Also add a configuration error I stumbled upon locally.

service/email.md

@@ -279,6 +279,13 @@ For debugging, you can make SMTP client sessions verbose in Postfix:
 example, you can try to force the authentication mechanism to
 `cram-md5` this way.
 
+If you can't send mail after this configuration and get an error like
+this in your logs:
+
+    Sep 26 11:54:19 angela postfix/smtp[220243]: warning: SASL authentication failure: No worthy mechs found
+
+Try installing the `libsasl2-modules` Debian package.
+
 ### Exim4 client configuration
 
 You can configure your Exim to send mails which you send `From:` your `torproject.org` email via the TPI submission service, while leaving your other emails going whichever way they normally do.