Can I subscribe someones IET email alias address to the list?
If it is an announcement list, (i.e. moderated) then there is no problem in them registering their email alias, however if it is a discussion list then they should use their real email address*. The reason for this is that as you cannot actually send messages from your email alias, any messages that they post will be treated like a non-member submission. * the exception to this rule is if someone has changed their reply-to to be their IET Email Alias, in which case the list will accept the message to be from the alias and send the message.