If the administrator has no morals then yes. It would be much easier to see mail that
has been saved in the inbox or sentbox for example. If you can read it in your mailbox
obviously so could an admin who have access to the same files.
Once in a while I am asked that by a client. I reassure them I do not have the desire
nor the time to read anyones mail and I highly respect their privacy.
Absolutely! In fact mail is sent as plain text on all internet email servers and
can be intercepted and any of number of places along the transmission path.
Where I am at, we run an automated process that keeps a running score on
outbound mail based on keywords found in user messages and alerts us
immediately if a certain threshold is identified indicating spamming, phishing,
or some other illegal activity and then we will assign a human administrator
from our security department to go investigate in those cases under probable
cause and always under the very strictest confidentiality rules.
If you are worried about anyone reading your mail anywhere, I would recommend
that you use PGP or some other form of encryption. That won't do you much good
on our networks since we have the means to decode most encryption standards
without the need for a pass key in a matter of a few seconds but most hosts won't
have the means to do what we do so that should block 99.9% of most any 3rd party
from intercepting or reading your email messages.