We would need to establish if there was a valid contract formed. As per Lord Wilberforce in The Eurymedon, an enforceable contract would have to consist of a valid offer and agreement, consideration, an intention to create legal relations and there has to be no vitiating factors.
The first issue would be as to whether there was an offer on the advertisement regarding the job of the PR officer. We may dismiss it as an offer and instead it should be merely an invitation to treat. This was established in the case of Patridge v Crittendon. This is also not similar to the facts of Carlill v Carbolic as there was a promise in return of an award for an act. The second issue would be whether there was an offer made by Jim when he called during the lunch break to mention that he was keen on joining. This may not actually amount to an offer as it is held that an offer has to be sufficient, clear and imperative as per Scammel v Ousten. Based on the facts where the pays and benefits were not discussed, it is likely to conclude that Jim made no offer.
Jessica then made an offer to Jim after the interview. As for acceptance, Postal rule will not come into effect, as there was no indication by Pei Ling or Jessica that the letter or acceptance is to be mailed but only to be hand delivered. Also, the message that Jim left on Pei ling’s voicemail may not equate to an acceptance, as it is not conveyed - as held in Gibbons v Proctor. It is also known from the fact that there was no indication that the acceptance was to be conveyed by phone or even through voicemail so it would seem unreasonable to impose on Pei Ling the duty. This would not conclude as an acceptance. So it would be arguable that the voicemail left by Jim did not amount to an acceptance. Thus, real valid acceptance was when Jim signed and emailed the pdf copy to Pei Ling as per
References: 1. http://statutes.agc.gov.sg/aol/home.w3p 2. http://www.e-lawresources.co.uk/ 3. http://legalresearch.westlaw.co.uk/ 4. Casebook on Contract Law, Jill Poole, Oxford, 11th edition 5. Contract Law, Ewan Mckendrick, Palgrave, 9th edition 6. http://www.lawgazette.com.sg/ 7. The Law of Contract in Singapore, Andrew Pang Boon Leong 8. http://www.lawonline.com.sg/