Merge pull request #23 from modalsource/QuinnDamerell-postal-disable-ipv6-sending

Replica: feat(smtp): add config option to disable sending email via ipv6

Author: lucaforni

app/senders/smtp_sender.rb

@@ -177,8 +177,8 @@ def resolve_mx_records_for_domain
   # @param endpoint [SMTPClient::Endpoint]
   # @return [Boolean]
   def connect_to_endpoint(endpoint, allow_ssl: true)
-    if @source_ip_address && @source_ip_address.ipv6.blank? && endpoint.ipv6?
-      # Don't try to use IPv6 if the IP address we're sending from doesn't support it.
+    if (@source_ip_address && @source_ip_address.ipv6.blank? && endpoint.ipv6?) || Postal::Config.smtp.disable_ipv6
+      # Don't try to use IPv6 if the IP address we're sending from doesn't support it or if it's disabled in the config.
       return false
     end
 

lib/postal/config_schema.rb

@@ -418,6 +418,11 @@ module Postal
         description "The e-mail to use as the from address outgoing emails from Postal"
         default "postal@example.com"
       end
+
+      boolean :disable_ipv6 do
+        description "Disalbles sending emails via IPv6, only IPv4 will be used"
+        default false
+      end
     end
 
     group :rails do