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MJ Ferdous

Ferdous has industry level experience on Microsoft Platform and has done several presentations and workshops on SharePoint. Prior to joining Microsoft, He worked as SharePoint Architect at BrainStation-23, OT Consulting, Rockwell Automation etc. Ferdous also worked as SharePoint Consultant and SharePoint Trainer for many organizations such as BASIS, Robi Axiata, etc.

He was the key organizer & speaker of “SharePoint Developer’s Conference 2013” & "SharePoint Community Day 2012" jointly with Microsoft. He is the author of several technical articles at code project, MS SharePoint Tips, Dev Media etc. He is also founder of SharePoint Experts Bangladesh user-group.

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SMTP Exception: 550 5.7.1 Unable to relay

I was trying to configure IIS 6 SMTP server for outbound mail in Windows Server 2008. I was getting error highlighted in below:

Telnet: 550 5.7.1 Unable to relay for

I am sharing my experience here how to solve this error. This is an error reply from your SMTP mail server. It indicates that your mail server is not configured to allow you to send mail through it. The standard port is 25 for SMTP connections. You can check your SMTP Server on SMTP port 25 using Telnet command.Open "MS-DOS prompt" or "command prompt". Just type the following command in the command prompt window and press "Enter":

telnet 25


The above highlighted line shows the error. So, You need to do the following if you get the SMTP error message "550 5.7.1 Unable to relay"

By default, the SMTP virtual server allows relaying only from authenticated users. This configuration is designed to prevent unauthorized users from using your Exchange server to relay mail. The virtual server's default configuration allows only authenticated computers to relay mail.

Change Default Relay Restriction:

Go to IIS6.0 Manager –> SMTP Virtual Server Properties –> Go to Access tab

Change to “All except the list below” to remove restriction. You also add Restricted IPs or domain name that you don’t want to allow.


This should solve your problem to allow to send email anywhere like gmail, yahoo or any other domain.

Print | posted on Monday, December 13, 2010 12:32 PM |



#  550 5.7.1 Unable to relay exchange 2007

hello , we have e2k7 in our company. we are trying to send email from outlook 2003 client with pop3 configuration we receive error unable to relay but its working fine with other outlook 2007 clients. we try to send email from command prompt same error we are getting in all pc.
5/31/2011 11:10 AM | mohammed dhastageer

# re: SMTP Exception: 550 5.7.1 Unable to relay

Thanks, that was helpful. One detail is missing though: On the access tab, press the relay button to configure the relay restrictions.
5/18/2012 9:53 AM | Jan

# re: SMTP Exception: 550 5.7.1 Unable to relay

Nice...solved our issue, however does it opens up any loop holes and do you have any advice for "configuring" relay and "restricted ips"
5/21/2012 5:50 AM | Dipanjan Ghosh

# re: SMTP Exception: 550 5.7.1 Unable to relay

Don't do this if your server is publically accessible, otherwise your server will be a host for mass spamming in no time...
11/27/2012 4:02 AM | J

# re: SMTP Exception: 550 5.7.1 Unable to relay

This is not a recommended solution because it opens up your mail server to relay any message it receives, effectively making it a spam magnet.
2/19/2014 8:09 AM | M

# re: SMTP Exception: 550 5.7.1 Unable to relay

You have to record an Accepted Domain in Exchange management named this : as an internal relay(!) even if the domain itself present as an authoritive domain
5/12/2014 7:14 PM | Zed

# re: SMTP Exception: 550 5.7.1 Unable to relay

Perfect, works on smtp server on server 2003, thks.
9/30/2014 10:47 PM | Josep Ramon Gimeno
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