We have a huge email distribution list that we use primarily to communicate to our customers new products, changes, any security or system notices, etc. Our email contact list is all legally obtainined through relationships with our customers over many years. No purchased email lists.
In the past we have tried constantcontact (expensive) or free server based scripts such as dadamail (a little slow even with 100mb) and some other services I won't mention here due to their poor performance (emails slow to get out, ended up on spam lists, etc).
Any suggestions for fast, affordable, email distribution in 2012 that doesnt cause spam problems? I can go either in house or use a third party service. Thanks in advance for your suggestions.