Mixing the two on one domain or stream means a bad campaign can block password resets. Separating them protects critical mail.
Mistake 1: Adding upsell banners to receipts, which reclassifies them as marketing under many laws#
Why it hurts: this undermines transactional email at the point where mailbox providers make their decision, and it is rarely surfaced by your own tooling until placement drops.
Fix: Send transactional mail from a dedicated subdomain (for example mail.yourdomain.com) or separate stream.
Mistake 2: Using one shared IP pool for both streams#
Why it hurts: this undermines transactional email at the point where mailbox providers make their decision, and it is rarely surfaced by your own tooling until placement drops.
Fix: Send marketing from a different subdomain (news.yourdomain.com).
Frequently asked questions#
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.