Illegal response received from the destination SMTP.

[rszabady]

I have a test environement in which I tested Ability mail server. We had very good success. We purchased accordingly.
However in our production environment we are getting the following error messages on specific domains.
I'm pretty sure it's a DNS server problem but i need to confirm before I go beat up my hosting provider.

Any feedback is greatly appreciated

Thu, 06 Dec 2007 16:21:17 -> Success: Action=[MX Lookup], Details=[DNS=10.200.139.67, Domain=aol.com: Found 4 records]
Thu, 06 Dec 2007 16:21:17 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=64.12.138.57: Connection accepted.]
Thu, 06 Dec 2007 16:21:17 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-02.mx.aol.com:25, IP=64.12.138.120: Connection accepted.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=205.188.159.216: Illegal response received, closing connection.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=64.12.138.57: Illegal response received, closing connection.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=64.12.138.57: Illegal response received, closing connection.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-02.mx.aol.com:25, IP=64.12.138.120: Illegal response received, closing connection.]
Thu, 06 Dec 2007 16:21:17 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-03.mx.aol.com:25, IP=205.188.109.56: Connection accepted.]
Thu, 06 Dec 2007 16:21:17 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-01.mx.aol.com:25, IP=64.12.137.184: Connection accepted.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-03.mx.aol.com:25, IP=205.188.109.56: Illegal response received, closing connection.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-01.mx.aol.com:25, IP=64.12.137.184: Connection closed unexpectedly or forced shutdown.]
Thu, 06 Dec 2007 16:21:17 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-02.mx.aol.com:25, IP=64.12.138.120: Connection accepted.]
Thu, 06 Dec 2007 16:21:17 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=64.12.138.57: Connection accepted.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-02.mx.aol.com:25, IP=64.12.138.120: Illegal response received, closing connection.]
Thu, 06 Dec 2007 16:21:17 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=64.12.138.57: Illegal response received, closing connection.]
Thu, 06 Dec 2007 16:21:17 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-01.mx.aol.com:25, IP=64.12.137.184: Connection accepted.]

[rob]

The response indicates the remote server has sent an non smtp comforming response. This generaly means that the response did not start with a 3 digit number. The only way you can verify this is to enable DEBUG logging for the outgoing mail, which will print a transcript of all commands and responses sent and received. I should note this will quickly fill your logs with huge amounts of data and slow the system down (effectively the mails are printed into the logs) but if you can afford the resources it may help find what is the source of the problem. Things you should suspect include AV scanners, firewalls, routers, your ISP still or even just AOL.

[rszabady]

Thank you for the responce. I tried a test email to a non AOL account. The replying SMTP server was the same in both my environments.
In my test environment I sent the email successfully. In my production environment I got the error. They are VERY different environement using different hosting providers (which means DNS servers, routers ,firewalls etc.)

I'll turn on debug mode. I have lots of disk space available. I'll post a reply after my test.

Thanks
Roy

[rszabady]

OK. Here is the outmail log with Debug enabled. It looks like a 220 response but then another line comes in with just ******* in it. Not sure why ?

Fri, 07 Dec 2007 19:14:18 -> Success: Action=[MX Lookup], Details=[DNS=10.200.139.68 10.200.139.67, Domain=aol.com: Found 4 records]
Fri, 07 Dec 2007 19:14:18 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-01.mx.aol.com:25, IP=205.188.156.248: Connection accepted.]
Fri, 07 Dec 2007 19:14:18 -> ***DEBUG*** -> Success: Action=[Recv Response], Details=[IP=205.188.156.248: 220-*******************************************************************************]
Fri, 07 Dec 2007 19:14:18 -> ***DEBUG*** -> Success: Action=[Recv Response], Details=[IP=205.188.156.248: ************************************************************]
Fri, 07 Dec 2007 19:14:18 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-01.mx.aol.com:25, IP=205.188.156.248: Illegal response received, closing connection.]
Fri, 07 Dec 2007 19:14:18 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=205.188.159.216: Connection accepted.]
Fri, 07 Dec 2007 19:14:18 -> ***DEBUG*** -> Success: Action=[Recv Response], Details=[IP=205.188.159.216: 220-*******************************************************************************]
Fri, 07 Dec 2007 19:14:18 -> ***DEBUG*** -> Success: Action=[Recv Response], Details=[IP=205.188.159.216: ************************************************************]
Fri, 07 Dec 2007 19:14:18 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-04.mx.aol.com:25, IP=205.188.159.216: Illegal response received, closing connection.]
Fri, 07 Dec 2007 19:14:18 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-03.mx.aol.com:25, IP=205.188.109.56: Connection accepted.]
Fri, 07 Dec 2007 19:14:18 -> ***DEBUG*** -> Success: Action=[Recv Response], Details=[IP=205.188.109.56: 220-*******************************************************************************]
Fri, 07 Dec 2007 19:14:18 -> ***DEBUG*** -> Success: Action=[Recv Response], Details=[IP=205.188.109.56: ************************************************************]
Fri, 07 Dec 2007 19:14:18 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-03.mx.aol.com:25, IP=205.188.109.56: Illegal response received, closing connection.]
Fri, 07 Dec 2007 19:14:19 -> Success: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-02.mx.aol.com:25, IP=64.12.137.168: Connection accepted.]
Fri, 07 Dec 2007 19:14:19 -> Failed: Action=[SMTP Transfer], Details=[Domain=aol.com, Host=mailin-02.mx.aol.com:25, IP=64.12.137.168: Connection closed unexpectedly or forced shutdown.]

[rob]

By the looks it would seem something is indeed breaking the SMTP transaction, and I would guess its a security devie (I have seen a similar thing with cisco routers). There are 2 issues I can see, firstly AOL is attempting to send a multiline response, but I do not see the final line which indicates the actual response. The second issue is that the lines of the response are being chopped into 2 lines, and so illegal responses are registering. What I recommend doing is checking your firewall, AV and router settings and ensure there is no excessive SMTP security measures enabled.

[rszabady]

You were right. My hosting provider found a firewall that was corrupting the data packets during inspection.
This is fixed and emails are flowing nicely now.

Thank you