Agree with 1 as it is limitation for legitimate use. For instance, when we diatributed flag rewards last campaign.

There was a user that merited 0.001 SBD rounded up for offering the downvote according to the reward shares. Yes, it's a trivial amount of SBD but they did earn it.

Adding a minimum transfer would hnder the ability to reward plankton and minnows for flag rewards. I could maybe save the amount until it reaches whatever threshold but that requires more accounting. If necessary, that is what we would do however.

Opting in or out is a good idea. I was suggesting perhaps opting out to only receive messages from those you follow for example but affording the user more flexibility would be a good thing.