Can I sign a PDF someone emailed me?
Short answer: Yes — open the attachment, share it to Signed (or import from Files/Mail), drop your signature and date, and share the signed PDF straight back.
Yes — this is the most common way Signed gets used, because most documents that need signing arrive as email attachments.
The flow on an iPhone:
- Open the attachment in Mail (or Gmail/Outlook — same idea).
- Tap the share icon and choose Signed (or "Save to Files" first — Signed imports from Files too).
- Drop your saved signature where it belongs; add the date (it fills itself in) and initials if needed.
- Export — Signed produces a clean, flattened signed PDF — and share it straight back as a reply.
The whole round trip takes about a minute, from the school car park or the train. No printer, no scanner app producing skewed grey photos of paper.
Honest alternative worth knowing: iOS Markup (the pen icon in Mail) can also scribble a signature on an attachment for free. It works in a pinch — the trade-offs are a rougher finger-drawn look each time, no saved signature library with styles, no AI option, and clunkier placement. If Markup covers your needs, use it; Signed is for when you want it to look right and take ten seconds every time after the first.
Full guide: how to sign a PDF from an email on iPhone.