Preflight
An automated pass over your file that catches missing fonts, low-res images, stray RGB, and no bleed before the press does.
See it
What it is
Preflight is the pilot's-checklist pass over artwork before it goes anywhere expensive. It looks for the mechanical failures a human eye skips: images under resolution, RGB left in a CMYK job, unembedded fonts, missing bleed, hairline strokes below 0.25pt, total ink coverage over the paper's limit, accidental overprint on white objects, one more spot color than you paid for.
InDesign runs a live preflight profile while you work, so errors show up as you make them. Acrobat Pro validates a finished PDF against PDF/X and fixes a subset automatically. The one that decides your fate is the printer's own profile, so ask them for their profile file and load it rather than guessing at their rules and losing two days to a rejected upload.
Gotcha: preflight is a spellchecker, not a proofreader. A clean report means machine-safe, not correct. The file can still be the wrong trim size, missing a fold panel, set in a substituted font that already looked wrong when you opened it, or carrying last quarter's price list. Green light, then read it again with human eyes.
Ask AI for it
Preflight this print file and return every issue as a checklist. Check for: images under 300 effective PPI, any RGB or Lab color left in a CMYK job, unembedded or substituted fonts, missing 3mm bleed, objects that touch the trim without bleeding past it, text outside the safe area, total ink coverage over the printer's published limit (it varies by output condition, commonly somewhere from 280% to 320%, so ask rather than assume 300%), strokes thinner than 0.25pt, unintended overprint or knockout on white objects, and spot colors beyond the agreed ink list. For each hit give the page, the object, the severity, and the exact fix.