According to an announcement by the Verdi services union, around 3,700 employees of Deutsche Post are participating in Saturday's warning strikes.
The union said postal delivery in the states of Lower Saxony, Bremen, Hamburg, Schleswig-Holstein, Mecklenburg-Western Pomerania, Brandenburg and Berlin would be affected. All in all, around 3.6 million letters and 150,000 packages will not reach their intended destinations on Saturday.
Over the past week, several warning strikes have delayed postal deliveries in several parts of the country. Service disruptions will likely continue next week.
The Verdi union is demanding Germany's postal service, Deutsche Post, provide job guarantees until 2011 for the 130,000 postal employees covered by public-sector wage agreements.
So far, Deutsche Post has offered to extend the guarantees for three months, which Verdi has rejected.
The union also wants ten shortened workdays for its members to compensate for the so-called "job destroying effect" of a planned increase in working hours from 38.5 to 41 hours for 55,000 of its workers.
Negotiations between the union and Deutsche Post will continue on Wednesday.