Do I need a dedicated IP address?
If you are sending a lot of email (greater than 50k per week), it is a good idea to have a dedicated IP in order to isolate your reputation. If you are sharing your IP, you are sharing your reputation with those other senders. In addition, ESPs rate limit your emails based on the IP. So if you are a high volume sender you should consider getting a pool of IPs. However, your reputation can also be hurt if you are not sending enough volume consistently from an IP - so it’s a tricky balance.
If your email sending is volatile with large spikes of volume, ESPs may assume those large spikes are spam. Also, if you overall volume is too low, they won’t acknowledge your reputation. Generally, if you are sending less than 5,000 emails per day, a shared IP may be the right solution.
The other thing to consider is using separate IPs for your bulk and transactional mail. There are a couple reasons for this:
- Delivery of time-sensitive transactional emails may get queued behind a large batch of bulk/marketing emails.
- Your transactional mail will be affected by the reputation created by your bulk/marketing mail.
Mailgun’s infrastructure mitigates some of the argument’s for a dedicated IP address. First of all, we are constantly monitoring our shared IP addresses for any reputation issues. We also allow you to schedule deliver of your emails by using the o:deliveryime parameter. This allows you to delay the delivery by using a time in the future and also allows you to jump other messages in your queue (say from a large bulk mailing) by using a delivery time of now().