Transactional email is triggered by a user action (receipts, password resets, alerts) and is exempt from most marketing consent rules. Marketing email promotes products and requires consent and unsubscribe links.
Do transactional emails need an unsubscribe link?
Not under CAN-SPAM if purely transactional. Gmail's bulk-sender rules still expect one-click unsubscribe for anything sent at volume, so many senders include it anyway.
Why does transactional email matter for deliverability?
Mixing the two on one domain or stream means a bad campaign can block password resets. Separating them protects critical mail.
What is the first step to get started with transactional email?
Send transactional mail from a dedicated subdomain (for example mail.yourdomain.com) or separate stream.
What is the most common transactional email mistake?
Adding upsell banners to receipts, which reclassifies them as marketing under many laws.