I am a little confused with this sentence "Sospechamos que María volverá con él". Do we not use el subjunivo of Sospechar i.e. Sospechemos que ...?

Compare:

Sospechamos que María volverá con él.         and

No sospechamos que María vuelva con él.

The subjuntive does not have anything to do with how much we suspect (or think, or doubt) - it is not about our level of OUR doubt.  We could be completely wrong about our suspicions, that is not what determines whether we use the subjuntive or not.  It is the action in the relative clause (Maria returning with him in the case above) that changes (indicative vs. subjunctive) depending on our level of uncertainly.  But again, we could be wrong about suspecting or not.  That makes no difference in the use of the subjuntive in spanish.  If we suspect (or think, or believe):  use the indicative mood in the relative clause.  If we don't suspect (or think, believe, etc) use the subjunctive mood.  Yeah, I had a hard time understanding the use of the subjunctive as well.  Still have problems with it!

Thanks very much Andrew.  You have explained it very well.  I will have to revisit the subjuntive vs the indicative. again.

All the best.

Anna