Contacting people using their MoD e-mail addresses can often be very frustrating if your e-mail includes an image such as a table or screenshot. No warning of delay / blocking is given, so the assumption is often that the addressee is being b****y rude and not responding. At least other organisations advise you that an e-mail is being delayed for screening, if their suspicious anti-spam software hasn't fathomed out that the e-mail is safe..
Which then leads to the same e-mail being resent to a private address, with all the associated risk.
I recall one meeting which included government people. Everyone was able to upload the relevant working documents except the MoD reps. So we printed off half a rain forest for them instead.....