The marketing team has been troubleshooting why an email was not sent to 10% of...

When troubleshooting why an email was not sent to a portion of the audience, it's important toconsider several factors beyond unsubscribes or held statuses. Bounced contacts from previous sends could be a significant reason why emails are not delivered. Bounces occur when an email cannot be delivered to an email address, which could be due to various reasons like an invalid email address or the recipient's mailbox being full. Reference:Salesforce Marketing Cloud Documentation