Fix MailWizz API access from Layered Popups - "Your IP address is not allowed to access this server"

Before explaining, we want to be very clear that we're a Web Agency and we're looking for long term providers that are affordable and also very experienced with lots of years working on hosting environments / very experts in WooCommerce and WordPress environment in this case. Very honest people, if you do this fine we will give you more tasks of other projects, since we're an agency and have multiple clients / projects, most of them based in WP. == General requirements for any freelancer in this kind of tasks - Have a good english (we also talk portuguese and spanish, just in case you use any of this languages). - Available to talk via voice in some special cases, where explain is 10x times faster than writing down. - You must have very advanced skills and experience in Virtualization and web hosting systems. - You must know how to handle the most used hosting apps and control panels, like SolusVM, Virtualizor, Proxmox, and also control panel like Plesk, CPanel, directadmin, Centos Web Panel, centminmod, etc. - You should know well OVH network platform model, so we don't have to go explaining how those systems work. - We want freelancers that fixes issues in minutes, not in hours. At least 5 years experience per area. - For next tasks we want you to bill us in minutes, since we will give you multiple tasks on same or different projects, then would be good to make a monthly payment or maybe make prepayment hours. All this if you show us u're good, of course. - We want you to be guru in optimization for large WooCommerce sites, where every cache layer is ultra important. <------------------- General info -------------------> == Techs / areas we want you to be a guru: - Google Insights / mobile / gtmetrix / pingdom optimization in WooCommerce WP area - Control Panels / Cpanerl / Plesk / CWP / Virtualizor / Proxmox / SolusVM - Apache / Nginx / Varnish / guru - System administration, scripting, automation. migration. Management of LVM and Thin LVM volumes. - Email management - SPF, DMARC, DKIM, PMTA, Email Deliverability, Postfix, exim, Gmail and Microsoft Postmaster Tools - MySQL - Must have large experience managing, hardening and optimizing sql services. - All kind of caching that helps to improve WooCommerce - Application Performance Management and Monitoring tools == Tasks for today: We get this error and need to fix it fast and easily. We get "Your IP address is not allowed to access this server" error from WP site (layered Popups) trying to connect the lists. Please very expertise WP guy. Thanks