How to sign a PDF in Gmail
Gmail has no signing of its own. A contract arrives as an attachment and the job is suddenly six steps long — so here is the short way, the free way, and the way that never leaves the message.
The free way, with what you already have
- 1Download the attachment. On Windows it lands in Downloads; on a Mac, wherever your browser puts it.
- 2Open it in a reader that can annotate — Preview on macOS, Microsoft Edge or Adobe Acrobat Reader on Windows.
- 3Add your signature. Preview can capture one from the trackpad or camera; Acrobat Reader's Fill & Sign draws or types one.
- 4Save the signed copy under a name you will recognise in an hour.
- 5Go back to Gmail, hit Reply, attach the signed file, and write the covering line.
Where it gets tiring. It works, and it is free. The cost is two context switches and a Downloads folder with three files called renewal_2026.pdf. On a phone it is worse: most mobile readers cannot sign at all, so the document waits until you are at a desk — which is how a two-minute countersignature becomes a two-day delay.
With MailGeni
The way that never leaves the thread
- 1Open the email in Gmail. MailGeni reads the attachment and flags it — a contract arrives labelled Sign Contract, with a Needs your signature banner.
- 2Click Sign. The PDF opens in a panel over Gmail, with your saved signature ready to place.
- 3Place it, fill any other fields the document needs, and send.
- 4It goes back as a reply on the same thread, with the signed PDF attached — no download, no upload, no second tab.
MailGeni produces a signed PDF and sends it back where it came from. It is not a qualified electronic signature — there is no embedded PAdES certificate — so for documents that specifically require one, use a service that issues them. For the ordinary run of renewals, engagement letters, consent forms and NDAs, a signed PDF returned on the thread is what the other side is waiting for.
Questions people ask
- Can I sign a PDF in the Gmail mobile app?
- Not with MailGeni — it is a browser extension, so it runs in Gmail on a desktop browser, including Chrome and Edge on a laptop. On a phone, the practical route is still a mobile PDF app that supports annotation.
- Does the document get uploaded anywhere?
- The document is read to work out what it is and where the signature fields are, and that request goes to the AI provider for that request only. MailGeni does not keep your document; temporary working files are swept daily. The privacy policy sets this out in full.
- What if I need them to sign, rather than me?
- That is the other direction: Request an e-signature sends the document out for signing, tracks who has opened it, and chases anyone who has not signed as the window runs down.
Checked on 15 September 2026.