diff --git a/config/environments/production.rb b/config/environments/production.rb
index 031c9d2cb..173318fe3 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -11,12 +11,13 @@ Rails.application.configure do
     config.action_mailer.delivery_method = :smtp
     config.action_mailer.smtp_settings = {
       address: smtp_address,
-      port: ENV.fetch("SMTP_PORT", "587").to_i,
+      port: ENV.fetch("SMTP_PORT", ENV["SMTP_TLS"] == "true" ? "465" : "587").to_i,
       domain: ENV.fetch("SMTP_DOMAIN", nil),
       user_name: ENV.fetch("SMTP_USERNAME", nil),
       password: ENV.fetch("SMTP_PASSWORD", nil),
       authentication: ENV.fetch("SMTP_AUTHENTICATION", "plain"),
-      enable_starttls_auto: ENV.fetch("SMTP_ENABLE_STARTTLS_AUTO", "true") == "true"
+      tls: ENV["SMTP_TLS"] == "true",
+      openssl_verify_mode: ENV["SMTP_SSL_VERIFY_MODE"]
     }
   end
 
diff --git a/docs/docker-deployment.md b/docs/docker-deployment.md
index 15ec58367..f92b80ca2 100644
--- a/docs/docker-deployment.md
+++ b/docs/docker-deployment.md
@@ -78,14 +78,15 @@ You can then plug all your SMTP settings from that provider into Fizzy via the f
 
 - `MAILER_FROM_ADDRESS` - the "from" address that Fizzy should use to send email
 - `SMTP_ADDRESS` - the address of the SMTP server you'll send through
-- `SMTP_PORT` - the port number you use to connect to that SMTP server (the default is 587)
+- `SMTP_PORT` - the port number (defaults to 465 when `SMTP_TLS` is set, 587 otherwise)
 - `SMTP_USERNAME`/`SMTP_PASSWORD` - the credentials for logging in to the SMTP server
 
 Less commonly, you might also need to set some of the following:
 
+- `SMTP_TLS` - set to `true` only for servers requiring implicit TLS (SMTPS on port 465); STARTTLS is used automatically by default so most servers don't need this
 - `SMTP_DOMAIN` - the domain name advertised to the server when connecting
 - `SMTP_AUTHENTICATION` - if you need an authentication method other than the default `plain`
-- `SMTP_ENABLE_STARTTLS_AUTO` - if you need to disable TLS on the SMTP connection
+- `SMTP_SSL_VERIFY_MODE` - set to `none` to skip certificate verification (for self-signed certs)
 
 You can find out more about all these settings in the [Rails Action Mailer documentation](https://guides.rubyonrails.org/action_mailer_basics.html#action-mailer-configuration).