Hey @spiffypaul! You could make this happen using a flow with the trigger “Placed Order”, and this flow filter: 
If someone is / is not in list: Is not in > &your main list] 

Then add a time delay, followed by an email that links to an embedded signup form or a subscribe page. 

Anyone who has unsubscribed in the past (or is suppressed for any other reason) will not receive this flow, but those with a “neutral” subscription status (have not subscribed or unsubscribed) would receive it. 

I hope this helps! 

 - Elise

Thanks Elise! Is it ok to do this with regards to GDPR? I didn’t think I could...

Hi @spiffypaul,

Thanks for your follow-up note and thank you @elisegaines for your post.

We have a pre-built filter in Klaviyo specifically for GDPR purposes. This filter is “is or is not within the EU”.

I recommend including “is not within the EU” as a flow filter in the flow Elise mentioned because GDPR requires informed and freely given consent before you send marketing emails to a contact. This may not necessarily be the case if somebody has placed an order and not otherwise agreed to be contacted for email marketing purposes. We have more information on sending according to GDPR regulations here. We also have a guide to collecting GDPR consent.

Thanks and have a great day.