Does it make sense to say:
Please consider this email as a meantime brief report.
If yes, why? and if no, how can it be fixed?
Edit By the above sentence, I want to say that this email is not the main report but, in the meantime, I just want to update you about the status and I'll send you another email later.
I also think Kris had a good notion to lead with "meanwhile".
The bigger problem might be the odd invocation of subjectivity in "please consider". It is an interim report; that fact is not up for judgement by the recipient. I would write something to the effect of:
"The main report is pending.* In the meantime, here's an update:"
*Bonus points if you tell them by when they can expect the full report.
– Tyler James Young Apr 10 '13 at 06:14