<div>
The recommendation pointed me to the solution.<br />
I resolved all DNS related issues and setup mail flow monitoring from MXToolbox.<br />
<br />
All seem to be working well now.
</div>


The recommendation pointed me to the solution.
I resolved all DNS related issues and setup mail flow monitoring from MXToolbox.

All seem to be working well now.

<div>
<div class="content wysiwyg-content">
Hello, I am running an Exchange 2010 messaging environment. For some months, I have been experiencing email delivery failures to some email addresses/domains. <br />
<br />
I get messages like :<br />
<br />
honolulu.directrouter.com rejected you message to the following email addresses:<br />
honolulu.directrouter.com gave the error: no such user here<br />
box607.bluehost.com rejected your message to the following email addresses: xxxxxx@domain.com<br />
em12345I.servername.com rejected your message to the following email address: yyyyy@domain.com <br />
em12345l.servername gave this error: please turn on SMTP authentication in your mail client or login to the IMAP/POP3 server before sending your message.<br />
server58.web-hosting.com rejected your message to the following email address: zzzzzzz@domain.com. server58.web-hosting.com gave this error: No such person at this address.<br />
<br />
For all the messages, if you try sending the same message in about 5 minutes, the message goes through.<br />
<br />
Has anyone experienced this ?
</div>
</div>


Hello, I am running an Exchange 2010 messaging environment. For some months, I have been experiencing email delivery failures to some email addresses/domains. 

I get messages like :

honolulu.directrouter.com rejected you message to the following email addresses:
honolulu.directrouter.com gave the error: no such user here
box607.bluehost.com rejected your message to the following email addresses: xxxxxx@domain.com
em12345I.servername.com rejected your message to the following email address: yyyyy@domain.com 
em12345l.servername gave this error: please turn on SMTP authentication in your mail client or login to the IMAP/POP3 server before sending your message.
server58.web-hosting.com rejected your message to the following email address: zzzzzzz@domain.com. server58.web-hosting.com gave this error: No such person at this address.

For all the messages, if you try sending the same message in about 5 minutes, the message goes through.

Has anyone experienced this ?

Email delivery challenge

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

Email Servers

An email client, email reader or more formally mail user agent (MUA) is a computer program in the category of groupware environments used to access and manage a user's email. A web application that provides message management, composition, and reception functions may internally act as an email client; as a whole, it is commonly referred to as webmail. Likewise, email client may be referred to a piece of computer hardware or software whose primary or most visible role is to work as an email client. Email clients can also have other systems, like calendars, notes and contact managers.