I have a bunch of email identities I have to use. My "email address" in Mail on both desktop and iPhone is set to a list, which causes the From field to be a menu.
On the desktop, it defaults to the one of those addresses that was in the To field of the message you're replying to, which is great; and on iOS, it used to just default to the last one used.
In iOS 6 it is doing... Something else.
My list of addresses is: email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com
And it is always defaulting to "firstname.lastname@example.org" now.
You will notice that that address is neither the first, last, nor alphabetically first or last in the list.
If it is to default to one address all the time (which sucks), then i at least want to pick which one, without having to delete all the others as options.
Any ideas what the fuck it is doing? Or how to apply the Stick of Correction?
Update, Sep 2013: A year later, iOS 6.1.4, and I still haven't found a solution to this, but I collected some more data.
I tried all 24 permutations of these four addresses: "email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org". The address it chose was always "email@example.com". This tells me that the order of the addresses in the field doesn't matter. I assume it is hashing them somehow and picking the first one in hash order.
If I take that set of 4 addresses, and add a random address to the end of the form "firstname.lastname@example.org" through "email@example.com", sometimes the address it picks switches from "firstname.lastname@example.org" to "email@example.com", or sometimes the new address at the end. I never got it to pick "firstname.lastname@example.org", but YMMV because your email addresses will hash differently than mine do.
Therefore, it does not seem to be the case that address A is always chosen in preference to address B. It's not merely hashing them and then sorting by the hash, or else the ordering of "email@example.com" and "firstname.lastname@example.org" would be stable. So something else is going on too. Maybe the "hash" is actually "address of the string", so malloc behavior is involved.
Some people suggested "put double-quotes around your default address". That does in fact make it pick that one (possibly the quote makes it hash to a lower number) but you can't send mail that way. Contrary to what others have reported, I get an "invalid address, send anyway?" error dialog. This may be IMAP-server-specific, I dunno.
Summary: this sucks.