Email Source: IONOS (formerly 1&1)

Homepage: https://www.ionos.com/

This source is known to forward email

forwarding notes:

Preserves DKIM signed email when forwarding. 1&1 provides hosting for applications, so this source may be more than just a forwarder.

Capable of generating DMARC compliant email for others

Yes

IONOS is a Hosting Platform and is often used by Application Development and Operations teams. Support for DMARC compliance may vary by the hosted environment, but general data from IONOS does show DMARC compliance via both SPF and DKIM.

Capable of signing email with DKIM for others

Yes

For DKIM configuration guidance please see https://www.ionos.com/digitalguide/e-mail/e-mail-security/dkim-domainkeys/

Capable of sending SPF compliant email for others

Yes

The link just below is a resource on how to configure this source to send SPF-aligned email on your behalf. You will complete this configuration by (1) following the source's instructions and (2) adding the required entries into your DNS. https://www.ionos.com/help/domains/configuring-mail-servers-and-other-related-records/using-an-spf-record-to-prevent-spam/