A spokesperson for the service said staff had been working hard to get deliveries back to normal after recent problems, including workers off sick.
Royal Mail has apologised again for any inconvenience that customers might have experienced.
A recent Royal Mail list of towns and cities that might experience more disruptions to service before Christmas did not include Oban.
A spokesperson for Royal Mail told The Oban Times: 'The vast majority of mail is delivered safely and on time. We aim to deliver to all addresses we have mail for, six days a week.
'In the Oban area, we have been experiencing some delays to service due to resourcing issues and high levels of sickness absence.
'We have been working hard to get our levels of service back to normal as soon as possible and the situation is improving. We apologise to customers for any inconvenience they may have experienced.'
Oban has been hit by a series of late and missing post - including birthday cards, overdue documents and booster appointments - one woman missed an operation after the Royal Mail delivered four first-class letters from a Glasgow hospital all at once – up to 14 days after the first one was posted and on the day her operation was due.
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