Mail delivery to anything xxxxx.xion.oxcs.net

[padair]

Since switching to use PMG as my preferred inbound/outbound mail relay I've noticed an issue. Any client email being delivered to any of the servers that are hosted by oxcs.net are being bounced back saying "lost connection with mx001.webcom.xion.oxcs.net[135.148.130.75] while performing the HELO handshake"

Server hostnames in logs are like this...

mx###.webcom.xion.oxcs.net
or
mx###.netsol.xion.oxcs.net
... etc. The start is often mx001, mx002 or mx003 etc. Not sure what the webcom or netsol stands for but the oxcs.net is "Open-Xchange.com".

Anyone else come across and issue sending email to those servers? I've used telnet on port 25 manually and connected to the server and manually type the HELO, rcpt to, mail from, etc commands it accepts the email and it sends so its not an IP blocking issue or anything like that as the manually email sent via telnet commands works.

Any advice appreciated.

Thanks, Paul.

 

[bfrd9k]

1. Do your MX, A, and PTR match postfix's HELO name?
2. Is your SMTP certificate valid, and not self-signed

From your PMG host do:

# Check your SSL dates (not before, after)
echo '' \
  | openssl s_client -starttls smtp -connect localhost:25 2>/dev/null \
  | openssl x509 -noout -text

# Check your own HELO (after you issue your HELO)
telnet localhost 25

Check your public DNS records...

# Check your MX
dig +short MX domain.tld @1.1.1.1

# Check your A using output from above
dig +short A mx1.domain.tld @1.1.1.1

# Check your PTR using output from above
dig +short -x 1.2.3.4 @1.1.1.1

Above assumes...

• Your email domain is domain.tld
• Your PMG hostname is mx1.domain.tld
• Your public IP is 1.2.3.4

 

[SteveSteve]

Since switching to use PMG as my preferred inbound/outbound mail relay I've noticed an issue. Any client email being delivered to any of the servers that are hosted by oxcs.net are being bounced back saying "lost connection with mx001.webcom.xion.oxcs.net[135.148.130.75] while performing the HELO handshake"

Server hostnames in logs are like this...

mx###.webcom.xion.oxcs.net
or
mx###.netsol.xion.oxcs.net
... etc. The start is often mx001, mx002 or mx003 etc. Not sure what the webcom or netsol stands for but the oxcs.net is "Open-Xchange.com".

Anyone else come across and issue sending email to those servers? I've used telnet on port 25 manually and connected to the server and manually type the HELO, rcpt to, mail from, etc commands it accepts the email and it sends so its not an IP blocking issue or anything like that as the manually email sent via telnet commands works.

Any advice appreciated.

Thanks, Paul.

I've dealt with the same thing, and I eventually ended up at the Hornetsecurity Vade website.

They have a tool to let them review your mail if you feel you are incorrectly blocked, because all of my PTR / SPF / DKIM / DMARC, etc. is correct, but, I'm in IT for a municipal government and we couldn't email other local municipal governments who use their product.

Their initial and final, no conversation back and forth allowed verdict was "your traffic is coming from a government IP range, and we're blocking you forever to protect our customers privacy".

One of the other local municipalities we email regularly was able to work with them as their customer to unblock us. (because they have their own, on premise mail system)

Another local municipality that uses Earthlink hosted email was not, and we've not been able to email them in years because of it.