The groupios Email Security Gateway from step3IT GmbH of Neumünster is a gateway that inspects incoming email before it reaches your mail server. According to the vendor, it combines several filtering layers against spam, malware, phishing and ransomware, self-learning detection, an intrusion prevention system and sender checks via DKIM, SPF and DMARC. Central certificate management and S/MIME encryption are integrated into the gateway. By the vendor's account, it stores no emails or mailboxes and works with Microsoft 365, Exchange, Postfix or other mail servers. It comes in two deployment models: on-premises in your own data centre, or as a service through the groupios Mare Cloud.
step3IT GmbH is headquartered in Germany; the website names no parent company in another country. The vendor states that the Mare Cloud is hosted entirely in Germany and free from the CLOUD Act; with the on-premises edition you decide where processing takes place. It is a commercial product, not open source. If you take it through an MSP partner, check where processing takes place.