The Trump transition emails
Over the weekend, Mueller obtained the transition emails from GSA (General Services Administration) which is federal, yet the Trump team have been crying out it was illegally done. However, as someone said if you send an email with a .gov extension then it is not private at all. In addition Flynn has probably handed over any copies of his emails already so it wasn't as if this wasn't going to happen.
Simply put, if there is nothing to find or hide then the transition team have nothing to worry about. An investigation means just that, to look into everything to make sure the job is done properly. We all expected the emails to be obtained, and it wasn't a surprise and Mueller with a hugely experienced legal team surely know whether their actions are legal or not. I don't think much of Trump's lawyers when one (John Dowd) claimed to have written a tweet (despite admitting he doesn't tweet or know how it works beforehand) that admitted Trump had knowledge of Russian meetings. Any good lawyer would never admit to anything without first being asked under oath, and never on a public platform.
Surely the transition team knew their emails would be scrutinized and looked at by external parties?