Insert dynamic merge tags

Insert dynamic merge tags into the welcome series to personalize subject lines and body copy. Put FirstName in the subject using the fallback 'there' for missing names, include LastOrderItem in the first paragraph but show 'a recent purchase' if empty, and show the loyalty tier badge inline only for subscribers with Loyalty=Gold or Platinum. Test the three variants using sample subscribers who lack each of these fields and give me the raw send preview for approval by Wednesday.

Before I finalize merge tags, make it easy for the reviewer to approve: surface which fields are missing most often, show how the subject line reads for subscribers missing FirstName, flag any tags that will expose backend codes instead of friendly names (like internal product IDs), and recommend fallbacks that sound natural. Pick one fallback per field to avoid inconsistent copy across the series.

In the welcome email preview, LastOrderItem showed an internal SKU instead of 'Monthly Subscription' for several test accounts. I'm afraid merge tags will leak internal codes to real subscribers. Where is that mismatch coming from — mapping in the export, a field value problem, or the tag itself — and what is the quickest corrective step to ensure user-facing labels appear instead of SKUs?

Across campaigns we've embarrassed a few customers by leaking internal codes or by showing raw fallbacks like 'there' inconsistently. Which habit is causing most errors — lack of canonical field values, poor previewing, or ad-hoc fallbacks — and what three practical changes will stop this: a canonical look-up table for display names, mandatory preview tests with empty-field samples, and a documented fallback style guide?