Setting an email to "operational" does the following
Note - when sending an operational message, Unsubscribed and Marketing Suspended leads will still be included in the "blocked from email" count on the schedule tab of the campaign.
When is it OK to use the operational setting?
Sending marketing email to unsubscribed addresses is illegal. For this reason, you should be extremely careful to only use this setting in extremely limited circumstances. Using this setting incorrectly violates Marketo's Terms of Service, and most antispam laws.
There may be legal consequences for using this setting incorrectly.
Good uses of the operational setting fall into two categories:
What's a transactional message?
A transactional message is part of a transaction that a lead has initiated and you are responding to.
Here's some examples of transactional messages:
What's a relationship message?
A relationship message describes something that affects your business relationship with the lead.
Here's some examples of relationship messages:
Operational messages should not contain any marketing content at all. In other words, do not use the operational setting to send a message that contains a receipt and a promotion, only a receipt.