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Offer letters: how a candidate checks the sealed file

An offer letter usually arrives as a PDF in email. Letterhead, a signature image, and a familiar filename do not prove the file came from the company. (Older titles asked “really from the company” — that overclaims.) A seal lets the candidate check Document integrity for the sealed file, see issuer cues such as Issuer Verified after business verification (Know Your Business, or KYB), and remember Identity is Not checked — without creating an account.

Updated October 10, 2026 · 5 min read

What the attachment cannot prove

A candidate is deciding whether to resign, relocate, or decline other interviews. The file in the inbox looks official: the company name, a logo, a salary, a start date, sometimes a scanned signature. Those details are easy to copy onto a different PDF. The filename can say Offer.pdf either way.

Email makes this worse. The message can come from a lookalike address, a compromised thread, or a forward that dropped the original. Nothing on the attachment itself tells the candidate whether this is the file the company issued.

What the candidate can check

The company seals the final offer. The candidate receives the verification link with the PDF. Opening the link needs no Opcilo account. The page shows who sealed the file and when. If the candidate also has the PDF, they can check that copy against the seal. A match means this file is the sealed one. A mismatch means it is not.

From the company’s file to the candidate’s check

1
Company seals the final offer
Safe path
The issued PDF gets a fingerprint and a verification link.
2
The offer travels
Email or another channel carries the PDF and the link.
3
Candidate opens the link
Safe path
No account. The page shows who sealed the file.
4
Candidate checks the PDF in hand
Safe path
Match: this is the sealed file. Mismatch: it is not.

The link is the check. The PDF name and the letterhead are not.

A short path for both sides:

Seal the offer you are actually sending
The company uploads the final PDF and shares the verification link with the letter. Seal the issued version, not an earlier draft.
Open the link before treating the PDF as the offer
The candidate opens the verification link in a browser. No account is required. They read who sealed it.
Check the file they received
If a PDF arrived separately, they check that copy against the seal. The filename is ignored. Only the bytes matter.

What a matching seal still does not prove

A match proves Document integrity for this sealed file and shows who sealed it. Issuer Verified appears only after business verification (Know Your Business, or KYB); Identity is Not checked. A match does not prove the employer is a real company, that the role exists, or that the salary will be paid. It is not a background check and not legal advice.

It also does not protect the candidate if someone who controls the company’s account seals a fraudulent letter. The seal will match those bytes. Read the issuer, and confirm the offer through a channel you already trust — the recruiter you spoke with, or the company’s careers site. The same limit is described in same filename, real-looking code.

For the sealing loop behind this check, see what document sealing is.

Frequently asked questions

Does the candidate need an account?

No. The verification link opens in a browser. The candidate can see who sealed the offer and check the PDF they received.

Does a logo or a signature image prove the offer?

No. Letterhead and a signature image can be copied onto another PDF. The seal check compares the file in hand to the file the company sealed.

Does a matching seal prove the job is real?

No. It proves this file is the sealed one and shows who sealed it. Confirm the company through a channel you already trust.