Error inotes: http not valid: 400 (Bad Request)

Hi all

I and all my users company are getting an error when send a new message from webmail. (inotes)

Domino Release 9.0.1FP3 (Linux/64)
$HaikuForm - 231.22
Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

10/04/2016 04.18.32PM Rilevato errore durante l’acquisizione dei dati: Stato HTTP non valido: 400 (Bad Request)

The mail template is mail90.ntf italian language

Domino server: 9.0.1FP3

I don’t know why is happening this

Any ideas?

Massimo M.

Subject: Are you going through a reverse proxy?

There was a previous issue in 8.5.1 FP4 in which the error would appear whether the user created, forwarded or replied to an email:

http://www-01.ibm.com/support/docview.wss?uid=swg21454229 http://www-01.ibm.com/support/docview.wss?uid=swg21454229

A troubleshooting step is to disable referral checking:

http://www-01.ibm.com/support/docview.wss?uid=swg21412267 http://www-01.ibm.com/support/docview.wss?uid=swg21412267

While you are on 9.0.1 and not 8.5.1, there may be something similar happening.