The action is the latest in a series of postal strikes to hit Scotland
Postal workers in Edinburgh and Stirling have staged the latest in a series of strikes in a row over working terms.
Meanwhile, staff in the Dundee East delivery office have walked out in protest at the sacking of a colleague.
About 125 workers in Dundee have been involved in the unofficial strike action.
The industrial action in Stirling and Edinburgh is part of a UK-wide campaign by the Communication Workers Union.
Royal Mail said about 160 staff at the Edinburgh mail centre and 26 delivery drivers took part in action.
Staff at delivery offices in Stirling, Anstruther, Irvine and Lochgelly are also due to strike on Saturday while workers at Dalkeith delivery office will strike on Monday.
The action is likely to cause disruption to deliveries in the affected areas.
However, Royal Mail said that more than 90% of its staff would be working normally over the coming days despite the strikes.
The ongoing dispute comes after the CWU and Royal Mail accused each other of reneging on a deal reached in 2007 aimed at modernising the service.
The union has accused bosses of forcing through change without consultation. Royal Mail said the changes were needed to meet the challenges of the 21st Century.
The service, which employs about 180,000 staff across the UK, is suffering as a result of increased competition from other operators, the impact of the growth of e-mail and a large pension deficit.
Meanwhile, Royal Mail said the action in Dundee would impact on deliveries in the DD4 and DD5 postcode areas.