[Grhm]

Hi, all.
For some time now I have adopted an excellent wheeze that I first heard described on this forum:
Each separate person, group, or organisation with which I need to correspond gets allocated a unique address on my domain from which all my e-mails to them are sent.
As a non-techie, I have found this surprisingly simple to do, and the benefits are multifarious. I recommend the practice to others.
There is just one situation, however, which crops up occasionally, where this way of doing things makes things a little irksome.
This is when I find I need to send a single message to several recipients who don't all have the same allocated 'sent from' address.
The only way I know how to do this at the moment is to send a separate message for each 'from' address.
That is to say, I start with a blank message, paste in the message text and message title, manually set the 'sent from' address and then manually enter the requisite 'to' address(es), send that message, then repeat for each of the other 'from' addresses.
Because I have defined my contact groups with a reasonable degree of logic, this situation doesn't crop up very often, but when it does, it can be a bit of a pain.
My question is this: is it possible to have a 'from' address defined for each contact, and for this scenario to be handled automatically?
In other words, can I set something up in Fastmail so that if I send a single message to multiple recipients, the system checks which 'from' address each recipient has been allocated and then makes each recipient's message appear to come from that address?
Failing that, does anyone have any other ideas how to simplify things in this situation?
Thanks,
Graham