Safe-Mail.net used to be very good for things that were important enough you didn't want to do it via your mailbox that you use for everyday conversations. I really liked them. The 3 MB limit was never an issue to me, since I rarely received any kind of attachment, for those type of things I just used Gmail or Yahoo.
What I liked about Safe-Mail was the simple yet easy interface, the fact they never ask you to store passwords (nor do they prompt Windows to ask if they should store your password), they give the precise date and time of the previous login (for me somewhat important), ... I felt, well, safe using them
That was before the big issues they had (in which I lost numerous emails), and before the number of spam became overwhelming as it is now. I somehow still sign in though, even though I am not using the account for anything important anymore.
I guess the service will remain a nice old-school but outdated service that will slowly phase out in the end, or they'll have to do a major restyling in order to make the service up-to-date.