LinuxQuestions.org - Forcing sendmail to use HELO

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Forcing sendmail to use HELO

My MX server is trying to send email to @itcbd.com but every time it is failing as it is first trying to EHLO and is being greeted with the following error message:

Code:

402 4.5.2 Error: command not recognized

It is obvious that the MX server for the @itcbd.com does not implement the EHLO command. For some reason, my MX server is not trying HELO after encountering the error message. I am using sendmail version 8.13.8. Is there any remedy?

MX servers for @google.com also does not implement the EHLO command, but my MX server manages to revert to using HELO and send emails to @google.com without any issue.

Is there any way I can instruct sendmail to use HELO by default?

I think you are getting confused or are misunderstanding.

An MX is for clients to determine how to send mail. So your Sendmail system is an MX in the receiving aspect. For sending mail, it is an SMTP client or MTA.

Both domains you indicate accept EHLO:

Code:

$ host itcbd.com 

itcbd.com has address 116.212.108.236

itcbd.com mail is handled by 10 mx-in-01.telnet-bd.com.



$ telnet mx-in-01.telnet-bd.com 25

Trying 116.212.104.91...

Connected to mx-in-01.telnet-bd.com.

Escape character is '^]'.

220 mx-in-01.telnet-bd.com ESMTP server of Telnet Communication Limited (Telnet). Sending Unsolicited Commercial or Bulk E-mail or SPAM to/from TELNET Computer Network is Strictly Prohibited. Any Attempt Of This Type Of Abuse Will Cause From Termination Of Network Connectivity Up To Activity Of Law Enforcement Agencies.

EHLO example.com

250-fortune-01.telnet-bd.com

250-PIPELINING

250-SIZE 20480000

250-VRFY

250-ETRN

250-ENHANCEDSTATUSCODES

250-8BITMIME

250 DSN

quit

221 2.0.0 Bye

Connection closed by foreign host.



$ host google.com

google.com has address 72.14.207.99

google.com has address 209.85.171.99

google.com has address 64.233.187.99

google.com mail is handled by 10 smtp3.google.com.

google.com mail is handled by 10 smtp4.google.com.

google.com mail is handled by 10 smtp1.google.com.

google.com mail is handled by 10 smtp2.google.com.



$ telnet smtp3.google.com 25        

Trying 64.233.183.25...

Connected to smtp3.google.com.

Escape character is '^]'.

220 smtp.google.com ESMTP

EHLO example.com

250-smtp.google.com Hello mail.sample.net [10.0.0.1], pleased to meet you

250-ENHANCEDSTATUSCODES

250-PIPELINING

250-8BITMIME

250-SIZE 20000000

250-STARTTLS

250-DELIVERBY

250 HELP

quit

221 2.0.0 smtp.google.com closing connection

Connection closed by foreign host.

Looks like EHLO is supported to me!

Thanks for helping me get the terms right. EHLO does not work from my end:

Code:

[root@mx2 ~]# telnet smtp3.google.com 25

Trying 64.233.183.25...

Connected to smtp3.google.com (64.233.183.25).

Escape character is '^]'.

220 smtp.google.com ESMTP

EHLO example.com

500 5.5.1 Command unrecognized: "XXXX example.com"

quit

221 2.0.0 smtp.google.com closing connection

Connection closed by foreign host.

[root@mx2 ~]# telnet mx-in-01.telnet-bd.com 25

Trying 116.212.104.91...

Connected to mx-in-01.telnet-bd.com (116.212.104.91).

Escape character is '^]'.

220 mx-in-01.telnet-bd.com ESMTP server of Telnet Communication Limited (Telnet). Sending Unsolicited Commercial or Bulk E-mail or SPAM to/from TELNET Computer Network is Strictly Prohibited. Any Attempt Of This Type Of Abuse Will Cause From Termination Of Network Connectivity Up To Activity Of Law Enforcement Agencies.

EHLO example.com

402 4.5.2 Error: command not recognized

quit

221 2.0.0 Bye

Connection closed by foreign host.

[root@mx2 ~]# telnet mx-in-01.telnet-bd.com 25

Trying 116.212.104.91...

Connected to mx-in-01.telnet-bd.com (116.212.104.91).

Escape character is '^]'.

220 mx-in-01.telnet-bd.com ESMTP server of Telnet Communication Limited (Telnet). Sending Unsolicited Commercial or Bulk E-mail or SPAM to/from TELNET Computer Network is Strictly Prohibited. Any Attempt Of This Type Of Abuse Will Cause From Termination Of Network Connectivity Up To Activity Of Law Enforcement Agencies.

HELO example.com

250 fortune-01.telnet-bd.com

quit

221 2.0.0 Bye

Connection closed by foreign host.

[root@mx2 ~]#

There is some firewall or SMTP proxy in the way stripping the EHLO and replacing it with XXXX. Can you disable this borked appliance?

@Mr. C.

Thanks a lot!!!

Our Internet Gateway router was only allowing "RFC 821 SMTP commands". I have managed to fix it.