I received this message in the Activity Details for several people who soft bounced a recent email " 554 5.4.5 [internal] Delivery not attempted (message expired)".Does anyone know what that means? Did I do something wrong? Does Marketo keep trying to send the email? This happened to a lot of people on this email, and I don't know how to explain this because I know I will get questions. Thanks!

Hi Stephanie,I ended up contacting Marketo support and they told me it basically means that the server we were trying to deliver to was not accepting emails at the time and so it "soft bounced" it. Marketo continues to try again after the first attempt about an hour later, then about two hours later, and so on until approximately 36 hours have passed. Marketo then marks the email as "soft bounced" from pending in your results and records that message in the activity log details.She said we could try resending since sometimes a receiving server is throttling email at the time although it may just consider this as spam based on past emails to leads on that domain who have marked your emails as spam. She also recommended creating a smart list to identify if certain leads are chronically soft bouncing and evaluate if we want to continue to try to send to those addresses or delete those leads.For example:smart listfilter: email bounced soft > minimum number of times (depends on your frequency of sending) > in past x months.