Take this as you will, I'm aware there's a counter argument for everything. But when it comes to restricting actions players can preform, it *always* hurts honest players more than it does the other kind.

Let's look at a few examples that don't really help the *real* players and are just a pain in the arse. Mind you, I'm not QQ'ing about these, just point them out as examples to point out that game restrictions designed to effect bots/spammers generally only hurt the real players.

Mail:
I can only send mail to people on my friends list, I can't have 2 of my toons logged in at the same time, therefor I can't send mail to myself. Likewise I can't send mail to anyone else without adding them to my friends list, meaning if I want to send someone a quick message, or an item or what not, I can't do it without first adding them. The only plus to this is that I can't receive spam messages, they will still spam in shout/yell/say/tells, so this really solves nothing other than I have to go though the pain of actually adding someone before I can send them a legit message. Also, since they seem to have 60 bajillion accounts, they just log 2 on, use a teleport hack, trade, makes no difference to them.

AFK timer:
Point in fact, the only people this really is ever going to kick is the DPS doing something else waiting for duty finder to pop. It's not going to do anything at all to gil spammers or bots.

Speed Reduction on Stealth:
Just makes it take longer to get from point A to the gathering point. Botters use stealth so that enemies don't aggro them while they don't have to worry about the speed reduction since they just teleport from gathering point to gathering point. Nothing against this, but see no purpose in it.

No click to blacklist function:
Really, the fastest way for me to stop my screen getting spammed is to click on their name, given I can manage to hit it blindly as it flies by, and then change /tell to /blist add " then push the end key, backspace, ", finally enter, and then I have to actually confirm that I want to add them? This one only effects real players. I don't even want to know what someone who just started playing for the very first time thinks the second they hit the actually city from the starting quest.
Lets take a moment to look at this one, what have other games done? Restrict the level you have to be before you can shout? That's even worse. Bots/spammers will just cheat anyways, so that does nothing. Add a "report spam" button, most games that have this, the report spam button does nothing but add the person to a personal ignore list, you'll still see that same spammer sitting around spamming if you take them off ignore 3 days later. What's something that could actually work? Add a "Report RMT" button to the menu that comes up when you click a name in chat, then when you click this button, it can add said player to ignore list, just like other games, and then start an internal timer on that person, then if X amount of people click report on that person in Y amount of time, put them on a global mute list, and register their account for review by your RMT team for account deletion. Sure, that can be abused by players collectively, but if it is, there was probably a reason for it. Keeping a system where you can't send the same message in shout twice over X amount of time will help reduce that abuse, as well as an normal 'blacklist' option in the player chat pop out menu. Of course then it will only be a matter of a few days before they realize what's going on and start doing a delete/recreate every 5 mins.

What's a really good solution to all of it?
Have people that are paid to monitor the servers around the clock for this kind of stuff.
Don't want to hire someone? I'm sure there's a whole boat load of players who would be more than willing to click a button on spammers to globally mute them with out being paid anything to do so. If you do go that route, just make sure they are people that are required to have things such as a security token, and willing to face consequences of abusing that power. Myself being one such.