Issue Error code: (31) include: or redirect= caused unlimited recursion

[daanse]

Hi, i have noticed this few Lines in Maillog if some specific Email will be send to my Mailbox.
Its always that same Mail (Mailflow Check from a Monitoring System)

Any Ideas why this spf gets an Error?

Sep 15 13:41:34 webhost spf[20658]: Starting the spf filter...
Sep 15 13:41:34 webhost spf[20658]: Error code: (31) include: or redirect= caused unlimited recursion
Sep 15 13:41:34 webhost spf[20658]: SPF result: neutral
Sep 15 13:41:34 webhost spf[20658]: SPF status: PASS
Sep 15 13:41:34 webhost /usr/lib/plesk-9.0/psa-pc-remote[21234]: handlers_stderr: PASS
Sep 15 13:41:34 webhost /usr/lib/plesk-9.0/psa-pc-remote[21234]: PASS during call 'spf' handler

System:
‪Debian 8.11‬
Plesk Onyx Version 17.8.11 Update #20
Postfix mail_version = 2.11.3

Mailserver SPF Settings: