If you use Mailchimp to send your email marketing then you are sending these emails from the Mailchimp domains and IP addresses. The bottom line is that if you have a specific need that requires that you send from your domain or IP address then Mailchimp isn’t for you.
Why using Mailchimp IP addresses means good delivery
The process of preparing an IP address to reliably deliver email is a slow process (this is commonly known as warming-up an IP address). Sending from an IP address needs to be throttled at first so that receiving email systems don’t suddenly get a mass amount of emails from an IP address that hasn’t been used for sending previously. Spam messages are such a massive problem that email receiving systems have to constantly be on the lookout for malicious or unwanted messages and the sending IP address is used as an indicator of trust that is built over time.
Mailchimp have two primary motives for using their own IP addresses to send all email marketing: Firstly Mailchimp are experts at delivering their clients EDM and they know how to properly warm-up and manage IP addresses to ensure the most reliable delivery. Secondly, Mailchimp have a great reputation that they want to maintain and it’s in their interests to ensure that their clients aren’t using any means that may tarnish Mailchimp’s reputation.
Will Mailchimp send my campaigns from only one IP address?
Mailchimp use over 20,000 IP addresses to send your campaigns. One way that Mailchimp use IP addresses to improve delivery rates is to throttle the use of each IP address so that a single IP address isn’t used to send a significant number of messages in a short space of time; for example, Mailchimp sent 19.9 billion emails in January 2016 with the biggest receiver being Gmail (including Google Apps email). If Mailchimp were to have an unethical customer that sends alot of campaigns to Gmail addresses then it’s highly likely that, if Mailchimp were using a single IP address, all Mailchimp customers delivery rates to Gmail would be negatively affected. By using multiple IP addresses Mailchimp improves delivery rates.
That Mailchimp use multiple IP addresses to send Email Direct Marketing means better delivery rates.