Same error here!
HostName: www.ensuelofirme.com
OS: Linux server.ensuelofirme.com 2.6.32-042stab116.2 #1 SMP Fri Jun 24 15:33:57 MSK 2016 x86_64
PHP: Linux 5.6.36 C
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=Yes, zlib_encode=Yes
WordPress: 4.9.6 es_ES UTF-8
WordPress Theme: Jakiro Child
WordPress Plugins: Gravity Forms, ActiveCampaign, Addendio PLUS, Advanced Custom Fields, AffiliateWP, Akismet Anti-Spam, Asesor de Cookies, Beaver Builder Plugin (Developer Version), Ultimate Addon for Beaver Builder, Better Search Replace Pro, iThemes Security, Broken Link Checker, Contact Form 7, Correos Express Plugin, Custom Base Terms, Custom Post Type Attachment ( PDF ), Custom Post Type UI, Custom Related Products for WooCommerce, Decent Comments, Duplicate Post, Enable Media Replace, Envato Market, Facebook Pixel, Force Regenerate Thumbnails, Google Analytics Dashboard for WP (GADWP), Google Image Sitemap Feed With Multisite Support, Google Mobile Sitemap Feed With Multisite Support, Google Video Sitemap Feed With Multisite Support, Heartbeat Control, Indeed Social Share & Locker Pro, WPBakery Page Builder, Loco Translate, MainWP Child Reports, MainWP Child, Media File Renamer, Metronet Tag Manager, Nice Search, No Frames, No Self Pings, openxwpwidget, Pagamastarde WooCommerce, PHP Code Widget, Post SMTP, Q2W3 Fixed Widget, Redirection, Remove Category URL, Slider Revolution, Optimize Database after Deleting Revisions, Sitesao Core, Templatera, Thrive Leads, TinyMCE Advanced, Testimonials WordPress plugin, UpdraftPlus - Backup/Restore, Web 2.0 Directory plugin, WC - APG NIF/CIF/NIE Field, WooCommerce Smart COD, optimizador.io, Woo Framework Shortcodes, WC - APG Weight Shipping, WooCommerce Google Analytics Integration, WooCommerce - Gravity Forms Product Add-Ons, WooCommerce Pay for Payment, WooCommerce PDF Invoices & Packing Slips, WooCommerce Prices By User Role, WooCommerce Product CSV Import Suite, WooCommerce Quantity Increment, WooCommerce Redsys payment gateway, WooCommerce Variable Product Description, WooCommerce Variation Swatches and Photos, WooCommerce, Wordfence Security, Yoast SEO, wp-addpub, WP Rocket, WP Sitemap Page, WPCustom Category Image, WPForms PayPal Standard, WPForms Stripe, WPForms
WordPress wp_mail_from Filter(s): wordfence::fixWPMailFromAddress
WordPress phpmailer_init Action(s): wpcf7_phpmailer_init, WC_Email_New_Order->handle_multipart, WC_Email_Cancelled_Order->handle_multipart, WC_Email_Failed_Order->handle_multipart, WC_Email_Customer_On_Hold_Order->handle_multipart, WC_Email_Customer_Processing_Order->handle_multipart, WC_Email_Customer_Completed_Order->handle_multipart, WC_Email_Customer_Refunded_Order->handle_multipart, WC_Email_Customer_Invoice->handle_multipart, WC_Email_Customer_Note->handle_multipart, WC_Email_Customer_Reset_Password->handle_multipart, WC_Email_Customer_New_Account->handle_multipart
Postman: 1.8.9
Postman Sender Domain (Envelope|Message): ensuelofirme.com | ensuelofirme.com
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: SMTP (smtps:oauth2://smtp.gmail.com:465)
Postman Active Transport Status (Ready|Connected): Yes | Yes
Postman Deliveries (Success|Fail): 3524 | 159
smtps:oauth2://smtp.gmail.com:465
220 smtp.gmail.com ESMTP r10-v6sm35902477wrm.15 - gsmtp
EHLO www.ensuelofirme.com
250-smtp.gmail.com at your service, [185.104.152.98]
250-SIZE 35882577
250-8BITMIME
250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
AUTH XOAUTH2 dXNl...
334 eyJz...
Kind regards.