I have a question regarding the deliverability issues we had with a recent campaign. We sent to a distribution list that normally has at least an 80% deliverability rate (and often higher than that) but had a 40% deliverability rate sending an email to that list recently. The majority of the bounces were soft – so perhaps this email got caught in spam folders? Do emails that go to spam get marked as a "soft bounce"?
No, you will never know if an email went to the Spam folder.
If the server rejects the email, it may show up in Marketo as Hard Bounced: Reason=Spam. You can find this out with the Email Bounced Reason filter or column in the smart list.
If most of your emails soft bounced, then check the Bounced Reason and look at your list. Are they all at the same firm? Are they all going to Europe during August (lots of holidays!).
Did something else happen?
In my smart list the email bounce reason for all of them is blank. It is really bizarre...
Most contacts are in the USA. Plus this list almost always has a high deliverability rate and we haven't changed whom the email is coming from or anything like that.
How long has it been since you launched the campaign? Have they been marked now as "Email Suspended"? If so, you might be able to gather some info from the "Email Suspended Cause".