Strikes are planned for Friday, 6 and Monday, 9 November.
Royal Mail managers and the Communication Workers Union (CWU) are meeting ahead of two newly announced 24-hour postal strikes.
The CWU has said all its members at the Royal Mail will strike on Friday, 6 and Monday, 9 November.
The two sides spent the weekend looking at proposals made by Brendan Barber, the general secretary of the TUC, who has been acting as a mediator.
The new dates follow three days of strikes last week.
Unlike the previous strikes, which have involved members in different roles striking on different days, the two new dates will be all-out action including up to 121,000 union members on each day.
The two sides, which are are locked in a row over pay and modernisation, are back at TUC headquarters this afternoon, following talks there last week.
Speaking on Friday, Mr Barber said proposals had been put to the union and the company - which they had agreed to look at over the weekend with a view to returning for further negotiations.
He added that both parties had agreed to his request that they did not comment publicly on negotiations while they were continuing.
On Saturday, 77,000 delivery and collection staff took part in industrial action, with an estimated 44,000 striking on Thursday.
On Friday 400 union members joined picket lines at sites in Plymouth, Stockport and Stoke.
These strikes followed two 24-hour stoppages the previous week.
Royal Mail says it is trying to modernise to compensate for letter volumes dropping by 10% every year as people switch to other forms of communication such as emails and texts.
It has shed 63,000 frontline postal staff in recent years and says it needs to cut more jobs as part of continuing modernisation plans.
The CWU agrees that job cuts are necessary, but disagrees over their extent, and over the future pay and working conditions of the workers that remain.
Royal Mail said the number of letters delayed as a result of the latest strikes had fallen from 50 million over the weekend to 25 million.