When emails bounce as spam, the lead that bounced is set to "Email Suspended." "Email Suspended" is a historical field. A more accurate name for this field would probably be "This email was suspended at some point in its history." The actual suspension only lasts 24 hours. To see if the lead is currently suspended, check the timestamp on the 'Email Suspended' field. If it is more than 24 hours ago, the lead is not currently suspended and can receive email from your Marketo instance. However, the "Email Suspended" flag will remain on the lead record for the purposes of future troubleshooting. It is not possible to set "Email Suspended" to "false" once it has been set to "true." The "Email Suspended Cause" field will provide the bounce message associated with the most recent spam bounce.