SNS topic not triggering Lambda

Question

I am attempting to set up a email-sending lambda function that is triggered by an SNS topic in cloudformation, but for some reason it is not working. I went in and checked all of the dependencies/permissions after the lambda & sns went up and everything seems to be in order, but when I publish to the topic nothing happens. When I manually test the lambda in the Lambda console, it works perfectly.

Cloudformation

"Resources": {
    "CloudformationEventHandlerLambdaExecutionRole": {
      "Type": "AWS::IAM::Role",
      "Properties": {
        "Path": "/",
        "Policies": [
          {
            "PolicyName": "CloudformationTrigger",
            "PolicyDocument": {
              "Statement": [
                {
                  "Effect": "Allow",
                  "Action": [
                      "ses:*"
                  ],
                  "Resource": [
                    "arn:aws:ses:*"
                  ]
                }
              ]
            }
          }
        ],
        "AssumeRolePolicyDocument": {
          "Statement": [
            {
              "Action": [
                "sts:AssumeRole"
              ],
              "Effect": "Allow",
              "Principal": {
                "Service": [
                  "lambda.amazonaws.com"
                ]
              }
            }
          ]
        }
      }
    },
    "CloudformationEventHandlerLambdaFunction": {
      "Type": "AWS::Lambda::Function",
      "Properties": {
        "Handler": "lambda_function.lambda_handler",
        "Role": {
          "Fn::GetAtt": [
            "CloudformationEventHandlerLambdaExecutionRole",
            "Arn"
          ]
        },
        "Code": {
          "S3Bucket": {
            "Ref": "Bucket"
          },
          "S3Key": "CloudformationEventHandler.zip"
        },
        "Runtime": "python2.7",
        "Timeout": "30"
      },
      "DependsOn": [
        "CloudformationEventHandlerLambdaExecutionRole"
      ]
    },
    "CloudformationEventHandlerLambdaInvokePermission": {
      "Type": "AWS::Lambda::Permission",
      "Properties": {
        "Action": "lambda:InvokeFunction",
        "SourceAccount": {
          "Ref": "AWS::AccountId"
        },
        "Principal": "sns.amazonaws.com",
        "SourceArn": {
            "Ref": "CloudformationTopic"
        },
        "FunctionName": {
          "Fn::GetAtt": [
            "CloudformationEventHandlerLambdaFunction",
            "Arn"
          ]
        }
      }
    },
    "CloudformationTopic": {
        "Type": "AWS::SNS::Topic",
        "Properties": {
            "DisplayName": "CloudformationIngestTopic",
            "Subscription": [
                {
                    "Endpoint": {
                        "Fn::GetAtt": [
                            "CloudformationEventHandlerLambdaFunction",
                            "Arn"
                        ]
                    },
                    "Protocol": "lambda"
                }
            ]
        },
        "DependsOn": [ "CloudformationEventHandlerLambdaFunction" ]
    }
  }

Python SES Lambda

import boto3

client = boto3.client('ses')

def lambda_handler(event, context):
    message = """
        Event:
        {}

        Context:
        {}
    """.format(event, context)

    response = client.send_email(
            Source='***censored***',
            Destination={ 'ToAddresses': [ ***censored***' ] },
            Message={
                    'Subject': {
                            'Data': 'CFMTest'
                        },
                    'Body': {
                            'Text': {
                                    'Data': message
                                }
                        }
                }
            )

Answer 1

The SourceAccount for the AWS::Lambda::Permission resource type is only meant to be used with Cloudwatch logs, CloudWatch rules, S3 and SES.
After removing this field from the CloudformationEventHandlerLambdaInvokePermission resource on your template, I am able to invoke the lambda function by publishing to the SNS topic.

Refer to this documentation for more information regarding lambda permissions