  Classical T Tauri stars (CTTS) differ in their X-ray signatures from older
pre-main sequence stars, e.g. weak-lined TTS (WTTS). CTTS show a soft excess
and deviations from the low-density coronal limit in the He-like triplets. We
test whether these features correlate with accretion or the presence of a disk
by observing IM Lup, a disk-bearing object apparently in transition between
CTTS and WTTS without obvious accretion. We analyse a Chandra grating spectrum
and additional XMM-Newton data of IM Lup and accompanying optical spectra, some
of them taken simultaneously to the X-ray observations. We fit the X-ray
emission lines and decompose the Ha emission line in different components. In
X-rays IM Lup has a bright and hot active corona, where elements of low
first-ionisation potential are depleted. The He-like Ne IX triplet is in the
low-density state, but due to the small number of counts a high-density
scenario cannot be excluded on the 90% confidence level. In all X-ray
properties IM Lup resembles a main-sequence star, but it is also compatible
with CTTS signatures on the 90% confidence level, thus we cannot decide if the
soft excess and deviations from the low-density coronal limit in the He-like
triplets in CTTS require accretion or only the presence of a disk. IM Lup is
chromospherically active, which explains most of the emission in Ha. Despite
its low equivalent width, the complexity of the Ha line profile is reminiscent
of CTTS. We present an estimate for the mass accretion rate of 10e-11 Msun/yr.
