A retrievable receiver for electromagnetic telemetry signals originating from a first wellbore is located in a second wellbore. The receiver uses a casing of the second wellbore as an antenna. A signal pickup unit is provided on a multi-conductor wireline in the second wellbore. The signal pickup provides sensors (e.g. electrodes) for detecting signals at plural locations along the second wellbore. Signal reception can be optimized by adjusting the position of the wireline in the second wellbore and/or selecting sensor(s) for use in receiving the telemetry signals. The receiver may lack any active electronics in the second wellbore.