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IP Address, Domain, and Email Whitelisting Guide

Ensure uninterrupted service by whitelisting necessary Domains, IPs, email addresses.

This guide provides the domain names, IP addresses, network ports, and email delivery information required to ensure reliable access to Schedule2.IT.

Schedule2.IT uses Cloudflare for DNS, security, and proxy services. Organizations with restrictive firewalls, web filters, or network security policies should review the requirements below.

1. Domain Whitelisting

Whitelist the following domain and wildcard entry to ensure Schedule2.IT and its subdomains can load:

  • schedule2.it
  • *.schedule2.it

Recommended: Use domain-based (FQDN) whitelisting whenever possible. This allows Schedule2.IT to continue functioning without requiring firewall changes when Cloudflare proxy IP addresses change.

2. IP Addresses and Ports to Whitelist

Schedule2.IT Origin IPv4 Addresses

The following addresses are maintained for Schedule2.IT infrastructure:

  • 74.113.139.23
  • 74.113.139.24
  • 74.113.139.25
  • 4.242.228.69

These are origin/infrastructure addresses and should not be confused with Cloudflare's public proxy IP addresses.

When accessing a Cloudflare-proxied Schedule2.IT website, users normally connect to Cloudflare rather than directly to these addresses.

Retain these addresses in existing allowlists where direct-origin connectivity is specifically required and authorized.

Cloudflare Proxy IPv4 Addresses

Schedule2.IT uses Cloudflare to proxy public web traffic. Organizations enforcing outbound IP-based restrictions may need to whitelist the following Cloudflare IPv4 ranges:

103.21.244.0/22 103.22.200.0/22 103.31.4.0/22 104.16.0.0/13 104.24.0.0/14 108.162.192.0/18 131.0.72.0/22 141.101.64.0/18 162.158.0.0/15 172.64.0.0/13 173.245.48.0/20 188.114.96.0/20 190.93.240.0/20 197.234.240.0/22 198.41.128.0/17

Cloudflare Proxy IPv6 Addresses

For organizations supporting IPv6, the following ranges may also need to be whitelisted:

2400:cb00::/32 2606:4700::/32 2803:f800::/32 2405:b500::/32 2405:8100::/32 2a06:98c0::/29 2c0f:f248::/32

Important: Cloudflare operates a shared global network. These IP ranges are not exclusive to Schedule2.IT and may change over time.

Organizations should preferably whitelist Schedule2.IT by domain rather than permitting unrestricted access to all services hosted on Cloudflare.

For the latest official Cloudflare IP ranges, visit:

https://www.cloudflare.com/ips/

Required Network Ports

  • TCP 443 (HTTPS) — Required for secure Schedule2.IT web application and API access.
  • TCP 80 (HTTP) — May be required for HTTP-to-HTTPS redirection.

HTTPS (TCP 443) is the preferred connection method.

3. Email Delivery: SendGrid Whitelisting

Schedule2.IT uses SendGrid for application-generated email notifications.

To help ensure successful email delivery, organizations may need to allow the following SendGrid sending IP address:

  • 168.245.8.152

Organizations using email security gateways, spam filters, or Microsoft 365 email protection should ensure legitimate Schedule2.IT messages are not incorrectly quarantined or rejected.

Email administrators should also review SPF, DKIM, and DMARC authentication results when troubleshooting delivery issues.

4. Retrieving Current Cloudflare IP Addresses

Cloudflare provides an API endpoint for retrieving its published IPv4 and IPv6 network ranges.

This can be useful for organizations that maintain automated firewall allowlists.

HTTP Request Example

GET /client/v4/ips HTTP/1.1 Host: api.cloudflare.com Accept: application/json

API Endpoint:

https://api.cloudflare.com/client/v4/ips

Successful Response Example

The following is an abbreviated example of the JSON response:

{   "errors": [],   "messages": [],   "success": true,   "result": {     "etag": "example-etag",     "ipv4_cidrs": [       "173.245.48.0/20",       "103.21.244.0/22"     ],     "ipv6_cidrs": [       "2400:cb00::/32",       "2606:4700::/32"     ]   } }

The actual response contains the published network ranges and should be used as the authoritative source for automated allowlist updates.

Failed Response Example

An API request may fail because of an incorrect endpoint, network connectivity issue, or other API error.

{   "errors": [     {       "code": 7003,       "message": "No route for the URI"     }   ],   "messages": [],   "success": false,   "result": null }

Note: A successful API response only confirms that Cloudflare's IP list was retrieved. It does not verify that Schedule2.IT is accessible or that a customer's firewall is configured correctly.

5. Troubleshooting Connectivity

If Schedule2.IT is inaccessible from your organization's network:

  1. Verify that schedule2.it and *.schedule2.it are permitted by your web filtering and DNS security systems.
  2. Confirm outbound HTTPS traffic on TCP port 443 is allowed.
  3. If using IP-based firewall restrictions, verify that the current Cloudflare proxy IP ranges are permitted.
  4. Check whether SSL/TLS inspection, proxy filtering, or security gateway policies are interfering with the connection.
  5. Test connectivity from an alternative network to determine whether the issue is specific to your organization's firewall.
  6. Contact Schedule2.IT support if the issue persists.

Security recommendation: Allow only the required destinations and ports. Avoid broadly disabling firewall, antivirus, or web security protections to resolve connectivity issues.

For additional assistance, please contact the Schedule2.IT support team.

Update History

October 9, 2026

  • Added Cloudflare proxy IPv4 and IPv6 ranges.
  • Clarified the distinction between Schedule2.IT origin addresses and Cloudflare proxy addresses.
  • Recommended domain-based whitelisting.
  • Updated Cloudflare API request and response examples.
  • Added network connectivity troubleshooting guidance.

May 11, 2026

  • Initial IP Address and Email Whitelisting Guide.