Keep getting bounceback message but the recipient is apparently receiving the emails...

Question

Delivery has failed to these recipients or groups:

xxxx
The email address you entered couldn't be found. Please check the recipient's email address and try to resend the message. If the problem continues, please contact your email admin.

Diagnostic information for administrators:

Generating server: exchange2019.livemail.co.uk

IMCEAEX-_o=First+20Organization_ou=Exchange+20Administrative+20Group+20+28FYDIBOHF23SPDLT+29_cn=Recipients_cn=******@winuk.mail
Remote Server returned '550 5.1.11 RESOLVER.ADR.ExRecipNotFound; Recipient not found by Exchange Legacy encapsulated email address lookup'

Original message headers:

Received: from winhex19beuk26.winuk.mail (10.10.160.33) by

 winhex19beuk24.winuk.mail (10.10.160.32) with Microsoft SMTP Server

 (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id

 15.2.1118.30; Wed, 5 Jul 2023 10:04:57 +0100

Received: from winhex19beuk26.winuk.mail ([fe80::acd9:4bec:c156:156e]) by

 winhex19beuk26.winuk.mail ([fe80::acd9:4bec:c156:156e%4]) with mapi id

 15.02.1118.030; Wed, 5 Jul 2023 10:04:57 +0100

Content-Type: application/ms-tnef; name="winmail.dat"

Content-Transfer-Encoding: binary

From:  xxxx

To: xxxx

Subject: Test

Thread-Topic: Test

Thread-Index: AdmvH7RMebtPrpmlTOGH3z/iPQRe4A==

Date: Wed, 5 Jul 2023 10:04:57 +0100

Message-ID: <******@cambridgecapitalgroup.co.uk>

Accept-Language: en-GB, en-US

Content-Language: en-US

X-MS-Has-Attach: yes

X-MS-TNEF-Correlator: <******@cambridgecapitalgroup.co.uk>

MIME-Version: 1.0

X-Originating-IP: [213.31.122.5]

Return-Path:

Answer 1

mxtoolbox said it was at ionos - it could be a subsidiary.

This message:

Server returned '550 5.1.11 RESOLVER. ADR. ExRecipNotFound; Recipient not found by Exchange Legacy encapsulated email address lookup' <<

Says the address cant be found. The recipient needs to fix it.

Answer 2

Hi Diane

Thank you for your message.

The address that bounces is the address I am sending to. It is with fasthosts.

How do I resolve this?

Regards

Jayne

Answer 3

Hi, I'm Diane and will be happy to help you today.

It appears the recipient is using hosted exchange from IONOS.

Is the address that bounces the address you are sending to? When an account is hacked, many hackers will set up rules to forward mail to their mailbox so they can monitor mail without logging in. (But it could also be legit, set up by the recipient.)

If the address that is bouncing is the address you sent the message to, the problem is with the ionos server. If you don't recognize the address, either the recipient is forwarding their mail or a hacker is. The sender (you) will get the bounce, not the person who is forwarding it.

-- Diane

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