For corporate mail, definitely use a separate setup. Lots of options here, and it's a question of what tools your org is comfortable using. We happen to be on E

For corporate mail, definitely use a separate setup. Lots of options here, and it's a question of what tools your org is comfortable using. We happen to be on Exchange. For transactional emails sent automatically by our web servers, we use Sendgrid. It's been very reliable and cheap (we have low volume and are grandfathered into their old pricing plan). Just setup your Postfix to point to their server with your credentials, and go. For newsletters that are hand-crafted, we're on Mailchimp, which as been pretty good. Their interface can be great for some people, and passable for others. It's designed to be very easy to use, but if you don't like one of their templates and need pixel-perfect control, it can be a little bit challenging. HTML editors is tough for everyone. To protect themselves and encourage good behavior, they will issue you a warning if you get more than 0.1% abuse (spam) complaints. This is generally not a problem if you're doing a double opt-in and not using imported lists. However, it's possible to make mistakes and cause problems. We ran a survey once to people who bought X, and manually pulled these email addresses out of our eCommerce engine. We sent them an email, but didn't scrub them against all of our unsubscribe lists, which is not a feature they have built-in -- you need to download all of the unsub/abuse lists and use Excel/scripts to remove them. We got a high abuse rate and they paused our account from sending more emails until we filled our their form explaining why it was high. Nice looking forms and default templates make Mailchimp a great place to start, especially if there's a marketing person that you can turn the whole thing over to. You can work with their APIs, which are adequate.