Allow List IP Addresses With Your Incoming (MX) Server

This page is a little technical, so if you are unsure what whitelisting is, be sure to read our blog post on allow listing/safe listing first. We also have additional information on allow-listing for Office 365 users here.

SMTP2GO sends out emails from a range of different IP addresses. The current IP addresses we use can always be found by looking at the SPF record for spf.smtp2go.com:

https://mxtoolbox.com/SuperTool.aspx?action=txt%3aspf.smtp2go.com

On the above page, you will see a series of IP address ranges, in the following format:
ip4:xyz.xyz.xyz.xyz/nn (this is called CIDR format)

If it is possible, it is often a good idea to have your incoming (MX) mail server allow-list the IP ranges shown on the above page. If your account has one or more dedicated IP addresses, you will only need to whitelist your account's dedicated IP addresses.

The benefits of whitelisting with your incoming mail server include:

• automatically bypassing unnecessary spam filters (as you have sent the emails, they shouldn't need to be scanned).
• automatically bypassing any blocklist checks (just in case any IP address ever features on a blocklist).

Updates:

January 2022: The outbound IP range 170.10.68.0/22 has been added.
November 2022: The outbound IP range 66.128.144.88/29 has been removed.
May 2023: The outbound IP range 158.120.80.0/21 has been added.