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That was indeed the case. &nbsp;As an SMTP amateur I'd never seen that before.<br />

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That was indeed the case.  As an SMTP amateur I'd never seen that before.


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I've got some emails bouncing back from specific internet recipients, so I decided to do the old &quot;telnet to the email server on port 25&quot; testing routine.<br />
<br />
I get connected fine, but when I enter either helo or ehlo I get &quot;501 Malformed HELO&quot; (or EHLO...I tried both).<br />
<br />
I thought this was strange, but I tried the same thing with our own domain and got the same response. &nbsp;Note that both we and the problem recipients use MXlogic, now MacAffee, as email proxies to filter spam (it's a paid service).<br />
<br />
We're lhshealth.com, the recipient domain is cambridgecap.com. &nbsp;DNS looks okay to me, and I've checked all the usual stuff...the address is correct if you do a reverse lookup on mail.lhshealth.com, and Exchange is sending mail.lhshealth.com in its banner. &nbsp;I did all my testing from CMD prompts on our Exchange box.<br />
<br />
Anyone know what these errors mean?
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I've got some emails bouncing back from specific internet recipients, so I decided to do the old "telnet to the email server on port 25" testing routine.

I get connected fine, but when I enter either helo or ehlo I get "501 Malformed HELO" (or EHLO...I tried both).

I thought this was strange, but I tried the same thing with our own domain and got the same response.  Note that both we and the problem recipients use MXlogic, now MacAffee, as email proxies to filter spam (it's a paid service).

We're lhshealth.com, the recipient domain is cambridgecap.com.  DNS looks okay to me, and I've checked all the usual stuff...the address is correct if you do a reverse lookup on mail.lhshealth.com, and Exchange is sending mail.lhshealth.com in its banner.  I did all my testing from CMD prompts on our Exchange box.

Anyone know what these errors mean?

501 Malformed HELO error during smtp troubleshooting via telnet

Interactions between email servers and clients are governed by email protocols. The three most common email protocols are POP, IMAP and MAPI. Most email software operates under one of these (and many products support more than one).  The correct protocol must be selected, and correctly configured, if you want your email account to work.

Email Protocols

Windows Server 2003 was based on Windows XP and was released in four editions: Web, Standard, Enterprise and Datacenter. It also had derivative versions for clusters, storage and Microsoft’s Small Business Server. Important upgrades included integrating Internet Information Services (IIS), improvements to Active Directory (AD) and Group Policy (GP), and the migration to Automated System Recovery (ASR).

Windows Server 2003

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.