Nodmailer.com works very nicely in my opinion. I'm not any kind of expert but the email headers I've taken a look at do not betray any kind of information which would give away my identity from what I've been able to tell.
It allows you to send fake emails with fake sender address, fake sender name, title and HTML code in the body of the email. Costs $5 to sign up I believe (for a month?) but its well worth it. I wouldn't recommend sending blocks larger than 100 at once though as Nodmailer sometimes has your connections time-out. Also, from my experience the only server which works right now is the one in the Netherlands but that may change or have changed already...