The database.exe process eats up all my memory and the polling in the database for new messages to send stops working. After we exit and restart the Ozeki server it is working again for some time.

Answer:

Some database drivers are not ready to handle long lived sessions with lots of queries. Often there is a problem with memory management in these drivers, for example they do not free up memory reserved for the result of SQL Select statements. To work around this issue, the database interface of OZEKI SMS can be reconfigured to terminate the database connection after a certain number of queries.

If you have problems with the database interface, open the "Special" tab of the database settings form and set the maximum number of queries that can be issued in a single database session.