Author: Evgeniy Berdnikov Date: To: exim-users Subject: Re: [exim] MS 365 "X-Matching-Connectors" header bounce error
Hello.
On Fri, Dec 10, 2021 at 09:46:37AM +0100, Martin Fischer via Exim-users wrote: > I would need your help. Messages from Exim to some MS 365 accounts hosted in Europe are bouncing when sent from MS Outlook or an Android client. Sending same message from Webmail (Roundcube) messages´is delivered but X-Matching-Connectors header is very big.
>
> 2021-12-09 14:07:23 1mvK4y-007pOT-RQ <= contact@??? H=(XXXXX) [XXXXXXXX]:62544 P=esmtpsa X=TLS1.2:ECDHE-ECDSA-AES128-GCM-SHA256:128 CV=no A=dovecot_login:contact@??? S=1216 id=!&!AAAAAAAAAAAuAAAAAAAAAGMiling04JAkZp
In this line "S=1216" means size of received message.
> JJsnUSnoBAMO2jhD3dRHOtM0AqgC7tuYAAAAAAA4AABAAAACL2Fs9vGAsTbjJEYiyeee1AQAAAAA=@atvirtual.nl T="MS Mail Bounce Report Verification" for postmaster@???
> 2021-12-09 14:07:23 1mvK4y-007pOT-RQ SMTP connection outbound 1639058843 1mvK4y-007pOT-RQ atvirtual.nl postmaster@???
Last line is definitely your custom logging, because Exim has no such string
in its sources (and the 1639058843 looks as ctime).
> 2021-12-09 14:07:25 1mvK4y-007pOT-RQ ** postmaster@??? R=dkim_lookuphost T=dkim_remote_smtp H=xxxxxx01b.mail.protection.outlook.com [104.47.17.138] X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=yes: SMTP error from remote mail ser
> ver after end of data: 554 5.6.211 Invalid MIME Content: Single text value size (32799) exceeded allowed maximum (32768) for the 'X-Matching-Connectors' header. [VI1PR0202MB2528.eurprd02.prod.outlook.com] [AS9PR06CA0096.eurprd06.prod.outl
> ook.com] [VI1EUR05FT058.eop-eur05.prod.protection.outlook.com]
Finally outlook.com reports 32799 bytes in a single header, while
the original mail has size 1216. So your Exim has modified message,
probably filling it with some garbage...
As you run some customized configuration, your custom code should be
inspected for header/body manipulations.
--
Eugene Berdnikov
