ON-PREM: Mail not working.

Hello everyone,
I have a problem with Space not sending emails.
MailHog is running correctly and I can access the UI.
I can curl to MailHog with: `curl http://mailhog:8025` from the docker on-prem container. So the connection is there.
It's also not my firewall, as I've allowed for port 1025 and 8025. The logs did not show any denials.
The email address is also correct.
This is the config added to the top of space.on-premises.conf:

mail {
   outgoing {
       enabled = true
       // protocol settings
       fromAddress = "space@space.example.com"
       host = "mailhog"
       port = 1025
       protocol = "SMTP" // "SSL" and "TLS" are also supported
       login = "space"
       password = "space"
       messageQueuePrefix = "mailQueue"
       // handling properties
       aggregationDelaySecs = 900
       rateLimitPerSecond = 3
   }
}

This has been added to docker-compose.yml under services:

    mailhog:
       image: mailhog/mailhog
       ports:
       - 1025:1025 # SMTP server port
       - 8025:8025 # UI port
       networks:
       - "frontend"

Here are the docker logs, as you can see MailHog is running:

2023-11-29 13:28:41 space-on-premises-mailhog-1        | [APIv1] KEEPALIVE /api/v1/events
2023-11-29 13:29:41 space-on-premises-mailhog-1        | [APIv1] KEEPALIVE /api/v1/events
2023-11-29 13:30:41 space-on-premises-mailhog-1        | [APIv1] KEEPALIVE /api/v1/events
2023-11-29 13:31:15 space-on-premises-space-1          | 2023-11-29 12:31:15.610 [[tx-pool] shared-16] INFO  c.server.mail.EmailVerification [trace_id=<redacted_trace_id_1>, orgDomain=space, txOriginName=EmailVerification/sendVerificationEmail, ip=<redacted_ip_1>, dbType=postgresql, clientTimezone=Europe/Amsterdam, principalName=<redacted_user_1>, principalId=<redacted_principal_id_1>, userId=<redacted_user_id_1>, orgId=<redacted_org_id_1>, dbKey=postgres, clientType=Browser, requestId=<redacted_request_id_1>, connectionId=<redacted_connection_id_1>] - Email: "<redacted_email_1>", profile: "<redacted_profile_id_1>" - attempting to send the verification mail
2023-11-29 13:31:15 space-on-premises-space-1          | 2023-11-29 12:31:15.611 [[tx-pool] shared-16] INFO  c.server.mail.EmailVerification [trace_id=<redacted_trace_id_1>, orgDomain=space, txOriginName=EmailVerification/sendVerificationEmail, ip=<redacted_ip_1>, dbType=postgresql, clientTimezone=Europe/Amsterdam, principalName=<redacted_user_1>, principalId=<redacted_principal_id_1>, userId=<redacted_user_id_1>, orgId=<redacted_org_id_1>, dbKey=postgres, clientType=Browser, requestId=<redacted_request_id_1>, connectionId=<redacted_connection_id_1>] - Email: "<redacted_email_1>", profile: "<redacted_profile_id_1>" - creating a new email verification request with id: <redacted_id_1>
2023-11-29 13:31:41 space-on-premises-mailhog-1        | [APIv1] KEEPALIVE /api/v1/events
2023-11-29 13:32:41 space-on-premises-mailhog-1        | [APIv1] KEEPALIVE /api/v1/events
2023-11-29 13:33:41 space-on-premises-mailhog-1        | [APIv1] KEEPALIVE /api/v1/events

Can anybody help me. I have no intelli-idea what to do next.