The only thing i don't understand is why this big law company got into that thing, i mean they have to know if this is just bullshit and this would harm their reputation.
A lot of the comments on this and other submissions blow this off as another lame attempt. But DLA Piper is not rookie law firm and if they actually are as confident as they say they are in this case, it is going to be interesting to watch.
Has a law firm ever not bragged about how confident they are that they'll win?
An email is just a text file. It could have been saved for all that time, or written yesterday. In the context of an outstanding accusation of forgery, more easily-forged documents have no evidential value.
A friend of Mark from this time could easily say if this is his writing style or not.
Mark's style could also be forged with a bit of frequency analysis so I'm not sure it proves anything (although it's admittedly unlikely).
The first thing that stands out to me is that the errors in punctuation (conveniently called out with "(sic)") are similar between both authors. For example, using a comma where one would normally end a sentence and omitting apostrophes in contractions and genitive constructions.