diff --git a/packages/core/src/initialization/__tests__/anchoring.test.ts b/packages/core/src/initialization/__tests__/anchoring.test.ts
index 3f136465c2..c880b123cd 100644
--- a/packages/core/src/initialization/__tests__/anchoring.test.ts
+++ b/packages/core/src/initialization/__tests__/anchoring.test.ts
@@ -1,6 +1,5 @@
 import { describe, expect, test } from '@jest/globals'
 import {
-  CustomMainnetCasError,
   DEFAULT_ANCHOR_SERVICE_URLS,
   makeAnchorService,
   makeAnchorServiceUrl,
@@ -14,29 +13,23 @@ import {
 
 describe('makeAnchorServiceUrl', () => {
   const CUSTOM_URL = 'https://cas.com'
+  const logger = new LoggerProvider().getDiagnosticsLogger()
 
   test('pass from config', () => {
-    expect(makeAnchorServiceUrl('hello', Networks.INMEMORY)).toEqual('hello')
+    expect(makeAnchorServiceUrl('hello', Networks.INMEMORY, logger)).toEqual('hello')
   })
   test('drop trailing slashes', () => {
     const trailingSlash = `${CUSTOM_URL}/`
     const doubleTrailingSlash = `${CUSTOM_URL}//`
-    expect(makeAnchorServiceUrl(CUSTOM_URL, Networks.INMEMORY)).toEqual(CUSTOM_URL)
-    expect(makeAnchorServiceUrl(trailingSlash, Networks.INMEMORY)).toEqual(CUSTOM_URL)
-    expect(makeAnchorServiceUrl(doubleTrailingSlash, Networks.INMEMORY)).toEqual(CUSTOM_URL)
+    expect(makeAnchorServiceUrl(CUSTOM_URL, Networks.INMEMORY, logger)).toEqual(CUSTOM_URL)
+    expect(makeAnchorServiceUrl(trailingSlash, Networks.INMEMORY, logger)).toEqual(CUSTOM_URL)
+    expect(makeAnchorServiceUrl(doubleTrailingSlash, Networks.INMEMORY, logger)).toEqual(CUSTOM_URL)
   })
   test('pass default by network', () => {
-    expect(makeAnchorServiceUrl(undefined, Networks.MAINNET)).toEqual(
+    expect(makeAnchorServiceUrl(undefined, Networks.MAINNET, logger)).toEqual(
       DEFAULT_ANCHOR_SERVICE_URLS[Networks.MAINNET]
     )
   })
-  test('throw on custom CAS on mainnet', () => {
-    expect(() => makeAnchorServiceUrl(CUSTOM_URL, Networks.MAINNET)).toThrow(CustomMainnetCasError)
-    const casInternal = 'https://cas-internal.3boxlabs.com'
-    expect(makeAnchorServiceUrl(casInternal, Networks.MAINNET)).toEqual(casInternal)
-    const casDirect = 'https://cas-direct.3boxlabs.com'
-    expect(makeAnchorServiceUrl(casDirect, Networks.MAINNET)).toEqual(casDirect)
-  })
 })
 
 describe('makeAnchorService', () => {
diff --git a/packages/core/src/initialization/anchoring.ts b/packages/core/src/initialization/anchoring.ts
index 1b89bb0588..21d5c1be82 100644
--- a/packages/core/src/initialization/anchoring.ts
+++ b/packages/core/src/initialization/anchoring.ts
@@ -40,22 +40,24 @@ export class UnusableAnchorChainsError extends Error {
   }
 }
 
-export class CustomMainnetCasError extends Error {
-  constructor() {
-    super('Cannot use custom anchor service on Ceramic mainnet')
-  }
-}
-
 const TRAILING_SLASH = new RegExp(/\/+$/g) // slash at the end of the string
 const MAINNET_CAS_URLS = [
   'https://cas-internal.3boxlabs.com',
   'https://cas-direct.3boxlabs.com',
+  'https://ceramic-prod-cas-api-gitcoin.3boxlabs.com',
   DEFAULT_ANCHOR_SERVICE_URLS[Networks.MAINNET],
 ]
-export function makeAnchorServiceUrl(fromConfig: string | undefined, network: Networks): string {
+export function makeAnchorServiceUrl(
+  fromConfig: string | undefined,
+  network: Networks,
+  logger: DiagnosticsLogger
+): string {
   const casUrl = fromConfig?.replace(TRAILING_SLASH, '') || DEFAULT_ANCHOR_SERVICE_URLS[network]
+  // Log a warning when using a custom anchor service URL on mainnet
   if (isMainnet(network) && !MAINNET_CAS_URLS.includes(casUrl)) {
-    throw new CustomMainnetCasError()
+    logger.warn(
+      `${casUrl} is not a standard Anchor Service URL for Ceramic mainnet.  Use a custom anchor service URL at your own risk. Note than an unreliable Ceramic Anchor Service can lead to data loss.`
+    )
   }
   return casUrl
 }
@@ -124,7 +126,7 @@ export function makeAnchorService(
   if (network === Networks.INMEMORY) {
     return new InMemoryAnchorService(config as any, logger)
   }
-  const anchorServiceUrl = makeAnchorServiceUrl(config.anchorServiceUrl, network)
+  const anchorServiceUrl = makeAnchorServiceUrl(config.anchorServiceUrl, network, logger)
   if (!config.readOnly) {
     const anchorServiceAuth = makeAnchorServiceAuth(
       config.anchorServiceAuthMethod,