style(rubocop): Style/SafeNavigation

lib/postal/message_db/message.rb

@@ -335,7 +335,7 @@ module Postal
       # Return the recipient domain for this message
       #
       def recipient_domain
-        rcpt_to ? rcpt_to.split("@").last : nil
+        rcpt_to&.split("@")&.last
       end
 
       #

lib/postal/smtp_server/client.rb

@@ -380,7 +380,7 @@ module Postal
           else
             idata = idata.to_s.sub(/\A\.\./, ".")
 
-            if @credential && @credential.server.log_smtp_data?
+            if @credential&.server&.log_smtp_data?
               # We want to log if enabled
             else
               log "Not logging further message data."