Path: ...!weretis.net!feeder9.news.weretis.net!i2pn.org!i2pn2.org!.POSTED!not-for-mail
From: hquest@hquest.pro.br (HQuest)
Newsgroups: comp.mail.sendmail
Subject: Re: [client] did not issue MAIL/EXPN/VRFY/ETRN during connection
Date: Mon, 29 Apr 2024 15:40:12 +0000
Organization: novaBBS
Message-ID: <2407dcab093db3d13420e7c35eb69189@www.novabbs.com>
References: <5c620d24d884ece84a12b62e2a4cbf45@www.novabbs.com> <v0h2fl$c0c$1@news.misty.com> <9c036674340a558c742c864a95764304@www.novabbs.com> <205d2ce2e6d1f636cb9afd2d26ae53fe@www.novabbs.com> <v0m8n8$m3c$1@news.misty.com> <f8786e2a92cc70d9c9cc28298e64f475@www.novabbs.com>
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HQuest wrote:
>> So there is some "screwup device" in front of sendmail?
>> It's broken, get rid of it.
>> 220 ***************************************************
>> That's an obvious violation of the RFC:
>>    Greeting       = ( "220 " (Domain / address-literal)
> Odd - the obfuscation ("Mask server banner") is shown as disabled, but still being enforced. Can confirm via a packet capture from the external border router.

Seems everywhere I look I find new security appliances. We identified the one with the obfuscation feature enabled and managed to get approval for disabling it. I still don't receive emails from Proofpoint, but this have fixed delivery issues with another provider (Mailchimp). Acceptable or not (as per a separate brief discussion), this is now up to our IS group to decide if a working solution outweigh their paranoia.

I'll continue to dig into this, now with some technical help from other manufacturers. The last bug search has raised many concerns.