Well I know with Aweber, if you go over a certain amount of spam complaints they will suspend your account. I send 1 a day with no problems. I know other who send 5 and are doing well too.
It also depends on your offer. If your offers are of quality and good, then your email list will be fine with receiving emails from you. Don't ever spend spam emails to them as you will be losing your subscriber as well as your auto responder will also not like it.