Task: Validate emails in Mautic with the One Simple API node

n8n workflow JSON:
{"id":86,"name":"Check for valid Mautic contact email","nodes":[{"name":"If is not new contact","type":"n8n-nodes-base.if","position":[780,460],"parameters":{"conditions":{"string":[{"value1":"={{$json[\"mautic.lead_post_save_new\"]}}","operation":"isEmpty"}]}},"typeVersion":1},{"name":"On Contact Identified","type":"n8n-nodes-base.mauticTrigger","position":[600,460],"webhookId":"a3ee0f93-2870-44e2-bb2f-0175433263b3","parameters":{"events":["mautic.lead_post_save_new"],"authentication":"oAuth2"},"credentials":{"mauticOAuth2Api":{"id":"54","name":"Mautic account"}},"typeVersion":1},{"name":"extract information","type":"n8n-nodes-base.itemLists","position":[980,480],"parameters":{"options":{},"fieldToSplitOut":"mautic.lead_post_save_new"},"typeVersion":1},{"name":"validate email","type":"n8n-nodes-base.oneSimpleApi","position":[1180,480],"parameters":{"resource":"utility","emailAddress":"={{$json[\"lead\"][\"fields\"][\"core\"][\"email\"][\"value\"]}}"},"credentials":{"oneSimpleApi":{"id":"33","name":"One Simple account"}},"typeVersion":1},{"name":"If the email is suspicious","type":"n8n-nodes-base.if","notes":"IF\ndeliverability is not good\nOR\nDomain is not valid\nOR\nEmail is Disposable","position":[1360,480],"parameters":{"conditions":{"string":[{"value1":"={{$json[\"deliverability\"]}}","value2":"GOOD","operation":"notEqual"}],"boolean":[{"value1":"={{$json[\"is_domain_valid\"]}}"},{"value1":"={{$json[\"is_email_disposable\"]}}","value2":true}]},"combineOperation":"any"},"typeVersion":1},{"name":"Send to Slack","type":"n8n-nodes-base.slack","position":[1560,460],"parameters":{"text":"=:warning: New Contact with Suspicious Email :warning:\n*Name: * {{$node[\"extract information\"].json[\"contact\"][\"fields\"][\"core\"][\"firstname\"][\"normalizedValue\"]}} {{$node[\"extract information\"].json[\"contact\"][\"fields\"][\"core\"][\"lastname\"][\"normalizedValue\"]}}\n*Email: * {{$node[\"extract information\"].json[\"contact\"][\"fields\"][\"core\"][\"email\"][\"normalizedValue\"]}}\n*Link: * https://mautic.my.domain.com/s/contacts/view/{{$node[\"extract information\"].json[\"contact\"][\"id\"]}}\n*Creator: * {{$node[\"extract information\"].json[\"contact\"][\"createdByUser\"]}}","channel":"#mautic-alerts","attachments":[],"otherOptions":{}},"credentials":{"slackApi":{"id":"53","name":"Slack Access Token"}},"typeVersion":1}],"active":false,"settings":{},"connections":{"validate email":{"main":[[{"node":"If the email is suspicious","type":"main","index":0}]]},"extract information":{"main":[[{"node":"validate email","type":"main","index":0}]]},"If is not new contact":{"main":[[],[{"node":"extract information","type":"main","index":0}]]},"On Contact Identified":{"main":[[{"node":"If is not new contact","type":"main","index":0}]]},"If the email is suspicious":{"main":[[{"node":"Send to Slack","type":"main","index":0}]]}}}