Delivery to the following recipients has been delayed

Usually, this indicates a problem on their end.  Perhaps the mailbox is full or their mail server is down.  However, if you are able to send mail to those addresses from other accounts (Hotmail, Yahoo, etc.), but not your Exchange server account, then there could be other issues.  I am assuming that your mail server is Microsoft Exchange.

Common causes include:

- The recipient's mailbox is full.  Usually, though, you would get a different error message.
- The address is invalid.
- Your mail server is on a blacklist.  This can happen if you have an open relay, or if you are using dial-up (many sites block mail coming directly from known dial-up IP addresses).  There are other ways to be added to public blacklists.
- Their mail server is on a blacklist.  Exchange does not include the feature to check against blacklists, but there are third-party add-ons which can do this, such as antivirus and antispam software.
- A firewall is blocking access to their mail server.  This could be your firewall or theirs.
- There are other routing problems between your server and their server.

Try the following.

- Open a command prompt.
- Type "NSLOOKUP" and press enter.
- Type "SET TYPE=MX" and press enter.
- Type in the domain name of the address that is giving you problems.  For instance, if you are trying to send to BillGates@microsoft.com, you would type "microsoft.com" and press enter.
- A list should appear.  This is a list of the mail servers (DNS MX records) that are assigned to that computer.  
- Look for the server name with the lowest preference number.  If they are all the same preference, just use one.  In our example, it is maila.microsoft.com.
- Type "exit" and press enter to quit NSLOOKUP.
- Try to ping the address.
- If successful, try to connect to the mail server manually:
- Type "telnet maila.microsoft.com 25" and press enter, substituting the appropriate server name.
- You should see a server banner message (see example).
<<< Do not make any typos on the next commands, or the commands will fail.  Backspace will not usually work.  If you mess up a command, press enter and type the command again. >>>
- Type "HELO" and press enter (you might not see what you type.  This is normal).
- Type "mail from:<youraddress@whatever.com>" substituting your address and press enter.
- Type "rcpt to:<billgates@microsoft.com>" substituting their address
- Type "data" and press enter.
- Type "Subject: Test message" and press enter TWICE.
- Type a short message.  When you are done, press enter, type a period, and press enter again to end the message.
- Type "quit" and press enter to exit.

NOTE: If everything works, then the message will be sent to the address.

Keep an eye out for any error messages during this process.

Your session should look like the following:

---------------------------------

C:\>nslookup
Default Server:  somednsserver.whatever.zzz
Address:  192.168.0.5

> set type=mx
> microsoft.com
Server:  somednsserver.whatever.zzz
Address:  192.168.0.5

microsoft.com   MX preference = 10, mail exchanger = maila.microsoft.com
microsoft.com   MX preference = 10, mail exchanger = mailb.microsoft.com
microsoft.com   MX preference = 10, mail exchanger = mailc.microsoft.com
maila.microsoft.com     internet address = 131.107.3.125
maila.microsoft.com     internet address = 131.107.3.124
mailb.microsoft.com     internet address = 131.107.3.122
mailb.microsoft.com     internet address = 131.107.3.123
mailc.microsoft.com     internet address = 131.107.3.121
mailc.microsoft.com     internet address = 131.107.3.126
> exit

C:\>ping maila.microsoft.com

Pinging maila.microsoft.com [131.107.3.125] with 32 bytes of data:

Reply from 131.107.3.125: bytes=32 time=91ms TTL=50
Reply from 131.107.3.125: bytes=32 time=87ms TTL=50
Reply from 131.107.3.125: bytes=32 time=88ms TTL=50
Reply from 131.107.3.125: bytes=32 time=87ms TTL=50

Ping statistics for 131.107.3.125:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 87ms, Maximum = 91ms, Average = 88ms

C:\>telnet maila.microsoft.com 25
220 inet-imc-01.redmond.corp.microsoft.com Microsoft.com ESMTP Server Tue, 18 May 2004 14:57:17 -0700
helo
250 nasmail02.psi.premier-system.com Hello [192.168.0.24]
mail from:<testing@bogus.zzz>
250 2.1.0 testing@bogus.zzz....Sender OK
rcpt to:<billgates@microsoft.com>
250 2.1.5 billgates@microsoft.com
data
354 Start mail input; end with <CRLF>.<CRLF>
Subject: Test message

This is a test
.
250 2.6.0 <MAILAPs6AvbEPDj00001101@maila.microosft.com> Queued
mail for delivery
quit
221 2.0.0 maila.microsoft.com Service closing transmission channel


Connection to host lost.

C:\>
---------------------------------


Try it out, and post any errors that you get.

- Will