They only send to me from gmail. Not from a macmail or their own domain. I have a gmail account too. To access it from anywhere on any computer, I have to be on the internet first.......and the From and To fields never change.
If you are using Gmail through your internet browser (Safari, Firefox, Chrome, etc) you do have to be on the internet to use Gmail. I don't want to overcomplicate this, but it is also possible to use Gmail through Apple's Mail App on the Mac, an iPad, or an iPhone. It is really easy to set that up.
Therefore - help me if I'm wrong about this - the only way to change a gmail account's To and From fields, one would have to go into that gmail account and twiddle about (which is a lot of twiddling about) to change anything like that.
If you are using the Gmail web interface through your browser it is quit difficult to change the From
field If you are using an email client such as Mail on your Mac you can change the From field to be the address of any email account you have set up in Mail. In either case all it takes the change the To field is to type in the email address of the person you are sending the email to.
Therefore, it doesn't matter whether they're on their iPad or iMac, they're still going onto the internet and accessing their gmail account in order to send me something, right?
Not necessarily, as I said it is easy to configure Mail on any OS X or iOS device to use a Gmail account, so they could be using either Mail or the Gmail web interface or Mail
Or, could they somehow be using the iPad and iMac to use their macmail to thence access gmail? If yes, how WEIRD is that? How extra-complicated is that? Why do that, that way?
It really isn't extra complicated, I have four email accounts from four different services and I access all of them through Mail so I only have to be familiar with one mail interface.