Community Forum emails bouncing back w 550 error msg

Regular Visitor emails bouncing back w 550 error msg

This has been happening for 2-3 weeks now. Messages I send to anyone with a email ID are bounced back.  


I can't find a reason or solution.


Here is a sample, with the individual's email hidden/modified:

************************************************************************************************* rejected your message to the following email addresses:
The address you sent your message to wasn't found at the destination domain. It might be misspelled or it might not exist. Try to fix the problem by doing one or more of the following:
  • Send the message again, but before you do, delete and retype the address. If your email program automatically suggests an address to use, don't select it.
  • Clear the recipient AutoComplete cache in your email program by following the steps in this article: Status code 5.1.1. Then resend the message, but before you do, be sure to delete and retype the address.
  • Contact the recipient by some other means (by phone, for example) to confirm you're using the right address. Ask them if they've set up an email forwarding rule that could be forwarding your message to an incorrect address. gave this error:
Not our Customer 


Diagnostic information for administrators:
Generating server:
Remote Server returned '550 5.1.1 Not our Customer'
Original message headers:
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;;
 s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version;
Received: from
 ( by
 ( with Microsoft SMTP Server (version=TLS1_2,
 cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id 15.20.567.18; Mon, 26
 Mar 2018 19:12:47 +0000
Received: from ( by ( with Microsoft SMTP
 Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id
 15.20.567.18 via Frontend Transport; Mon, 26 Mar 2018 19:12:47 +0000
Received: from
 ([fe80::91db:b3b5:9fb3:8676]) by
 ([fe80::91db:b3b5:9fb3:8676%14]) with mapi id 15.20.0609.012; Mon, 26 Mar
 2018 19:12:47 +0000
Subject: Fw: Final Foursomes for Tuesday, March 27th Bridges golf
Thread-Topic: Final Foursomes for Tuesday, March 27th Bridges golf
Thread-Index: AQHTxTERt1gUxF/sM0ST+JMSJO/XsqPi4iNO
Date: Mon, 26 Mar 2018 19:12:47 +0000
Accept-Language: en-US
Content-Language: en-US
x-incomingtopheadermarker: OriginalChecksum:CD6E3BE37223126CB73EAB9FAA103C346AEE744C4DF5A1EA1A193AAFA890CC28;UpperCasedChecksum:6CD1B5767B4868DBEDD69EC433F5A723C3E68C5B49DA6D3D5FEF64B3548553AF;SizeAsReceived:7030;Count:46
x-ms-exchange-messagesentrepresentingtype: 1
x-tmn: [iMe/Ld9jGzmscZD08wMAKgrn6qTl2x+n]
x-ms-publictraffictype: Email
x-microsoft-exchange-diagnostics: 1;SN1NAM01HT061;6:xSkOBnU65dsGgSaDd/k56pUYcAutzPMXTCtkLjerz0CjJe6jM04ZqtZRdOFo59hgKr1ygftqoDhENFUL86Xj6ZVhnk4UcytfrrTtYmkvdIC89COLavD7mhqO86qa/7pywMHjy2qvgeKvtMz7NI5p3UJFC2fy+RC6BJkfH7RQYRI/n8SU8UQY0S9tNYpEtUOKza7URGd8j0thK661D8bjf4+KCCyOVISl3MjE4K0CHg/6mONllR/usPuVrbWpFJjA4FPNbdLCp063ora7T8T7D/tcNf8xUa6nMBqxZTXbUKaNEYEcLqnuI8T0/ALsaFKqj8F+IIV1SUVl3JutJX4wPa1vB+oiyJ4IBqyYi81MPrA=;5:hEPhLdBHxyAtyD7CZmKw6YdLpf3iugTyIBDeDQlvhvoDy0PZu41gGPOPIPRPAFtde1u0yJAayuye+nnE/Y7/p8dFw44Nfa4PsRjo1uL4r7VB+DKigCPCUiXsv6zr+Ii5DUn5QJ2hOkGaQchrpodCC6uTWFmJTpgOp2/I4Eyf9wI=;24:xNKYZTmN0SsqsLJP9t3PyMgv2CRH6wti7N/D9JRy1/XFccpVkWK7bzlJ+Cvn4lOPyRzbBp9syruBSswSSo0ZHrRLGkNKIQWfa+EWTT4TVoc=;7:cLFn+HNCkqsc0BRN4PfS2B/iRSuXGzSWAZNHDEQ6afQVaB4qXQZSoHdH7qI+KkhK0IDhnjlhP/dEfAC1Dz5pWmuqEj7wx7nbYxrxp4EplkDcqJyXtpxgorYLdT/ENfXHZgxaCp8o4iaHnJIpI0fqWyksOZwUOJUhtvsA6bA9YiOiqBRwvk9IgvGSFcZay/sU3kXoome0B7+tfnM87lp6e7rf6rZNN/0ztMZmHYwQiohowmG/uaBmOKo8Y8nVwd8O
x-incomingheadercount: 46
x-eopattributedmessage: 0
x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(201702061078)(5061506573)(5061507331)(1603103135)(2017031320274)(2017031324274)(2017031323274)(2017031322404)(1601125374)(1603101448)(1701031045);SRVR:SN1NAM01HT061;
x-ms-traffictypediagnostic: SN1NAM01HT061:
x-ms-office365-filtering-correlation-id: bfe7ef9b-c8c7-45b9-3249-08d5934d8f7d
x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(444000031);SRVR:SN1NAM01HT061;BCL:0;PCL:0;RULEID:;SRVR:SN1NAM01HT061;
x-forefront-prvs: 06237E4555
x-forefront-antispam-report: SFV:NSPM;SFS:(7070007)(98901004);DIR:OUT;SFP:1901;SCL:1;SRVR:SN1NAM01HT061;;FPR:;SPF:None;LANG:;
x-microsoft-antispam-message-info: GNzF5beimWRpvRFryibWezS0zCDAWcbTEU344wzHSvPKhZ4iLh56cUmmnGoG/ybd+QKEaZkA3lmkeQqcs6qi057uOY9YmV4WgRbkMadv587u9QM7YXzEcGvJhZuuZum35Ti9Za2pBE8XvEqqPjQ3onuejw+vg3/DMQy3kdWDr05lryuiW99NpEWcALWOtoHi
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: multipart/alternative;
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: bfe7ef9b-c8c7-45b9-3249-08d5934d8f7d
X-MS-Exchange-CrossTenant-originalarrivaltime: 26 Mar 2018 19:12:47.1123
X-MS-Exchange-CrossTenant-fromentityheader: Internet
X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN1NAM01HT061

Re: emails bouncing back w 550 error msg

First, the error message clearly states that there is a problem with the address you are sending to.  Maybe there is a typo in it, or it's no longer valid etc.  Do you have some other email program you can try with like Yahoo or Gmail or something?  Does the same thing happen sending to the Comcast address?  550 series error messages deal with problems with the recipient's email address.

Regular Visitor

Re: emails bouncing back w 550 error msg

There were several emails to various addresses that bounced. I confirmed that all were spelled correctly. I even contacted one person to be sure I had their email correct. What I had used was correctly spelled. One of the emails that bounced was sent to my wife, whose email has been the same for years; it was spelled correctly. So the message that there is an error in the address is wrong. Somehow, that seems to be the root of this -- however an email address is checked for validity, it's failing sometimes. It is just for emails, so I infer that the problem is on Comcast's side.


The problem is intermittent. I sent a test message to my wife's email id yesterday. It succeeded without bouncing. So, at least for now, they're not bouncing.


I have not yet tried a separate email service like gmail. If I get more bounces, I will try this then. Thanks.

Regular Visitor

Re: emails bouncing back w 550 error msg

These bounced messages are happening again. email bounced yesterday. Email to france domain bounced today.


Yesterday's error reported as: gave this error:
Not our Customer 


Today's error reported as:

mwinf5c07 gave this error:
Adresse d au moins un destinataire invalide. Invalid recipient. OFR_416 [416] 

(basically just says it's an invalid recipient. But the recipient is correct.)


(The emails are going out using the servers, as I understand it -- beyond me...)


Official Employee

Re: emails bouncing back w 550 error msg

Could you send me a private message with a sample of some of the addresses you're attempting to send to?