Create conditional content blocks

Create conditional content blocks for the June promo so each subscriber sees the right hero: show the product A block to subscribers tagged ProductA-Interest, show product B block to ProductB-Interest, and show the generic hero to everyone else. Ensure fallbacks are plain text for email clients that block conditional content, test across three major clients, and provide a proof link plus screenshots for a subscriber in each tag group before I send Tuesday at 10 a.m.

Before I deploy conditional blocks, make the decision easy for the reviewer: surface which segments will see each block, estimate percentage of the send that will see personalized content, flag any blocks that will be empty if tags are missing, and point out where a viewer could accidentally see two blocks because of overlapping tags. Recommend a safe fallback and a guard clause to prevent duplicate exposures.

I set conditions for ProductA-Interest and for HighValue customers; a handful of subscribers are in both. I'm worried they'll see conflicting hero images or duplicate offers. Which condition should take precedence, how do I implement precedence without rewriting the whole template, and what copy change would reduce confusion if both blocks cannot be avoided?

We keep losing launch time because conditional content behaves inconsistently across templates and client tests. Where are we repeatedly making mistakes — ambiguous tag definitions, template complexity, or lack of fallback tests — and what three habits will avoid the delays: a simple priority matrix for conditions, a single template library with tested fallbacks, and a preflight checklist for conditional blocks?