diff --git a/core/server/services/mega/mega.js b/core/server/services/mega/mega.js
index 952bb81ccf..0f753bed8f 100644
--- a/core/server/services/mega/mega.js
+++ b/core/server/services/mega/mega.js
@@ -25,7 +25,9 @@ const events = require('../../lib/common/events');
 const messages = {
     invalidSegment: 'Invalid segment value. Use one of the valid:"status:free" or "status:-free" values.',
     unexpectedEmailRecipientFilterError: 'Unexpected email_recipient_filter value "{emailRecipientFilter}", expected an NQL equivalent',
-    noneEmailRecipientError: 'Cannot sent email to "none" email_recipient_filter'
+    noneEmailRecipientFilterError: 'Cannot sent email to "none" email_recipient_filter',
+    unexpectedRecipientFilterError: 'Unexpected recipient_filter value "{recipientFilter}", expected an NQL equivalent',
+    noneRecipientFileterError: 'Cannot sent email to "none" recipient_filter'
 };
 
 const getFromAddress = () => {
@@ -141,7 +143,7 @@ const addEmail = async (postModel, options) => {
         break;
     case 'none':
         throw new errors.GhostError({
-            message: tpl(messages.noneEmailRecipientError, {
+            message: tpl(messages.noneEmailRecipientFilterError, {
                 emailRecipientFilter
             })
         });
@@ -352,12 +354,18 @@ async function getEmailMemberRows({emailModel, memberSegment, options}) {
     // `paid` and `free` were swapped out for NQL filters in 4.5.0, we shouldn't see them here now
     case 'paid':
     case 'free':
-        throw new Error(`Unexpected recipient_filter value "${recipientFilter}", expected an NQL equivalent`);
+        throw new errors.GhostError({
+            message: tpl(messages.unexpectedRecipientFilterError, {
+                recipientFilter
+            })
+        });
     case 'all':
         filterOptions.filter = 'subscribed:true';
         break;
     case 'none':
-        throw new Error('Cannot sent email to "none" recipient_filter');
+        throw new errors.GhostError({
+            message: tpl(messages.noneRecipientFileterError)
+        });
     default:
         filterOptions.filter = `subscribed:true+${recipientFilter}`;
     }
@@ -534,7 +542,8 @@ module.exports = {
     sendTestEmail,
     handleUnsubscribeRequest,
     // NOTE: below are only exposed for testing purposes
-    _partitionMembersBySegment: partitionMembersBySegment
+    _partitionMembersBySegment: partitionMembersBySegment,
+    _getEmailMemberRows: getEmailMemberRows
 };
 
 /**
diff --git a/test/unit/services/mega/mega.test.js b/test/unit/services/mega/mega.test.js
index 3f09d9ccaa..26afa7747b 100644
--- a/test/unit/services/mega/mega.test.js
+++ b/test/unit/services/mega/mega.test.js
@@ -2,7 +2,7 @@ const should = require('should');
 const sinon = require('sinon');
 const errors = require('@tryghost/errors');
 
-const {addEmail, _partitionMembersBySegment} = require('../../../../core/server/services/mega/mega');
+const {addEmail, _partitionMembersBySegment, _getEmailMemberRows} = require('../../../../core/server/services/mega/mega');
 
 describe('MEGA', function () {
     describe('addEmail', function () {
@@ -35,6 +35,36 @@ describe('MEGA', function () {
         });
     });
 
+    describe('getEmailMemberRows', function () {
+        it('addEmail throws when "free" or "paid" strings are used as a recipient_filter', async function () {
+            const emailModel = {
+                get: sinon.stub().returns('paid')
+            };
+
+            try {
+                await _getEmailMemberRows({emailModel});
+                should.fail('getEmailMemberRows did not throw');
+            } catch (err) {
+                should.equal(err instanceof errors.GhostError, true);
+                err.message.should.equal('Unexpected recipient_filter value "paid", expected an NQL equivalent');
+            }
+        });
+
+        it('addEmail throws when "none" is used as a recipient_filter', async function () {
+            const emailModel = {
+                get: sinon.stub().returns('none')
+            };
+
+            try {
+                await _getEmailMemberRows({emailModel});
+                should.fail('getEmailMemberRows did not throw');
+            } catch (err) {
+                should.equal(err instanceof errors.GhostError, true);
+                err.message.should.equal('Cannot sent email to "none" recipient_filter');
+            }
+        });
+    });
+
     describe('partitionMembersBySegment', function () {
         it('partition with no segments', function () {
             const members = [{