The decision on whether strike action will go ahead is likely to surface just hours before the action is planned to start.
Three, 24-hour strikes are planned for Thursday, Friday and Saturday this week, if the CWU and Royal Mail cannot resolve the dispute over employment, pay and modernisation of the postal service.
The proposed strike action follows a two-day walkout last week.
Yesterday, the CWU said it would take legal action against the Royal Mail, over the decision to take on temporary staff to clear the backlog caused by the strikes.
Last week the Royal Mill announced it would take on an additional 30,000 temporary staff to deal with the Christmas period and the backlog created by strike action.
Retailers including John Lewis, eBay, and Argos have investigated alternative delivery services to avoid the disruption caused by the strikes in the run up to Christmas.
The London Chamber of Commerce says the two-day strike last week cost UK business an estimated £200m in lost income. The Direct Marketing Association says the walkouts could cost £10m in cancelled, postponed or lost direct mail campaigns.