This article also answers:

Can I send payment reminders to customers paying offline?

Yes, you can remind your customers about their Payment Due invoices by checking the enabling the Enable offline dunning option under Settings >> Revenue recovery >> Dunning for offline payments. 

If you have Net D configured, the reminder emails will be sent after the configured number of days. 

More information here

Note: This feature is supported on the V1 & V2 emails.