Can I email a contact from the CRM if they have opted out of emails?

If you assign a subscription to a contact then they opt out of receiving emails from you, you can still send an email to them from their contact record in the CRM by giving them a one time legal basis. 

• Click the name of the contact. 
• On the contact record, click the email tab. 
• Click Add a subscription to assign a subscription. Enter a subscription type, assign lawful basis for communicating with the contact, and provide an explanation for consent. 
• Or, click Give one-time legal basis. 

With GDPR enabled in your account, unsubscribe links are added to your sales emails by default. This includes sequences and one-to-one emails sent from a contact record in the CRM. 

If they have opted out of all email and unsubscribed from a sales email, then you will not be able to send any form of email to this contact.