Whitelisting Our IP Addresses With Office 365

To ensure that emails delivered from SMTP2GO to Office 365 are not incorrectly labelled as spam, it is a good idea to add our IP Address Ranges to the Allowed List in the Connection Filtering Policy within the Office 365 Exchange Admin Center (EAC).

This process is slightly different to other whitelisting as Office 365 limits the size of CIDR ranges to the /24 range and over. This article lists our IP addresses in ranges supported by the Office 365 administrator settings interface.

The main benefit of whitelisting is that your email will automatically bypass unnecessary spam filters (as you have sent the emails).

To add SMTP2GO IP addresses to the Office 365 "IP Allow List":

  1. Sign into Office 365 and click "Admin", then under "Admin Centers", click "Exchange"
  2. Under the "Protection" list, choose "Connection Filter"
  3. Click the "Edit" button which looks like a pencil
  4. Choose "Connection Filtering" on the left side menu
  5. Click the plus "+" symbol and add an IP range from the list below and click "OK"
  6. Repeat step 5 until the IP ranges below have been entered
  7. Check the "Enable Safe List" checkbox
  8. Finally, click "Save"

Instructions for the new Exchange Admin Center:

  1. Sign into Office 365 and go to the "Security Center" https://security.microsoft.com/homepage 
  2. In the left side menu under “Email and collaboration” go to “Policies and rules
  3. Click the “Threat policies” option
  4. Under “Policies” click “Anti-spam”
  5. Click “Connection filter policy (Default)” so the options appear on the right side and then click the “Edit connection filter policy” link
  6. Add our IP ranges from below to the “Always allow messages from the following IP addresses or address range” section
  7. Check the “Turn on safe list” checkbox
  8. Finally, click “Save”


IP Ranges:


The current IP addresses we use can always be found by looking at the SPF record for spf.smtp2go.com:


Extra information on this process including a video demonstrating the steps required can be found in the Microsoft Technet Library.

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