[MlMt] Limiting Mailbox Scope to Current Account

[Bill Cole]

On 17 Apr 2016, at 11:57, Dave Smith wrote:

> Honestly, I was shocked to discover it was even possible, for messages 
> to
> be moved to another email account. Never seen a client with that 
> ability on
> any platform.

Classic Mac Eudora could from its earliest IMAP support (v3?)
Thunderbird could since at least v2
Mulberry always could.
Apple Mail can on iOS since at least v4 and Yosemite and I'm pretty sure 
always could.
K-9 on Android could circa 2010-2012 (probably still can)
ChatterEmail v3 could on PalmOS

So, it isn't exactly an unusual or novel feature.