Questions

Can you help with corrupt email attachments in incoming mail?

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Can you help with corrupt email attachments in incoming mail?

marty_dunne
Hello,

Since the 15 Sept 2011 90% of email attachments (pdf's, jpegs, office documents etc) received

are reporting corrupt errors and cannot be opened.

We have a small office network with Windows 2008 Dell server controlling DHCP, routing and remote access

and file services etc. All pc's and Mac's access web etc through the server. We are using outlook, entourage

and Mac mail and all are receiving corrupted mail.

If I bypass the server and connect a PC directly to our router all mail received is perfect

so server would appear to be at fault.

I have disabled anti-virus, firewall, file backup software etc on the server but no change.

I have un-installed and re-installed routing and remote access but no change.

All sent emails with attachments are fine.

The only event noted on the 15 Sept was windows update downloaded 2008 server updates

but did not install (this is how it is setup).

I did install and un-install these updates but no change.

Anybody any ideas - all help would be much appreciated.

Martin

Clarifications

markp24

hi just want to see if i visualize this correctly,
The individual client access mail vial the web/isp/exchange server outside your network, you have the mail being routed thru the onsite windows 2008 server then to the client (working as a firewall/ids/proxy) between the users and the isp?. The windows 2008 server only does DHCP and Routing/remote access and nothing else?

is it possible one of the Nics went bad or maybe you need change the nic setting from auto/auto to 100/full., maybe the nic driver, or the ethernet cable?

just thoughts.

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    0 Votes
    robo_dev

    If so, what version of exchange?

    You stated:
    "If I bypass the server and connect a PC directly to our router all mail received is perfect"

    That would imply that you have no mail server? Or are you using Exchange to simply forward email?

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    0 Votes
    markp24

    is it possible one of the Nics went bad or maybe you need change the nic setting from auto/auto to 100/full., maybe the nic driver, or the ethernet cable?

    just thoughts.

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    0 Votes
    marty_dunne

    Yes you are correct, we have no exchange server on site, not enough clients to merit.
    There are 4 companies sharing the building network infrastructure so our server acts
    to firewall and isolate our network segment from the rest.
    All emails are accessed directly from isp mail server externally, through our server,
    to each internal client.
    I have checked and replaced all cables but no change.
    Everything else works fine i.e web access/ftp/outgoing mail/server file sharing etc except incoming mail attachments are corrupt (some get through ok).

    thanks for all replies
    Martin

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    0 Votes
    roxy786

    Which AV are you using?
    Check with Email Filter option and Level of Security applied to it..

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    0 Votes
    markp24

    hmm this one is a stumper. have you tired checking for packet retransmits on the network, (using a sniffer or drom the router logs) I have rebooted a server uning a linux live cd and went to a terminal and typed "ethtool -S eth0"
    (etho may vary) and it shows a chart with all kinds of great info , but i found i had a nic that was retransmitteding packets due to it being set to auto/auto for the duplex setting (i ended up having to set it to 100/full and the same on the cisco port, seems the negotiation protocols arent 100% perfect).
    everythingworked fin on the server except for when i tried to copy a large file, i would get network resource no longer avaiable in windows . so i wonder if this is similar to your issue. (worth a look)
    not sure how to get the same in windows without a deticated diag tool for that Nic or maybe using a sniffer.

    but heres a sample for the linux command output

    NIC statistics:
    rx_packets: 1669993
    tx_packets: 627631
    rx_bytes: 361714034
    tx_bytes: 88228145
    rx_errors: 0
    tx_errors: 0
    rx_dropped: 0
    tx_dropped: 0
    multicast: 0
    collisions: 0
    rx_length_errors: 0
    rx_over_errors: 0
    rx_crc_errors: 0
    rx_frame_errors: 0
    rx_fifo_errors: 0
    rx_missed_errors: 0
    tx_aborted_errors: 0
    tx_carrier_errors: 0
    tx_fifo_errors: 0
    tx_heartbeat_errors: 0
    tx_window_errors: 0
    tx_deferred: 0
    tx_single_collisions: 0
    tx_multi_collisions: 0
    tx_flow_control_pause: 0
    rx_flow_control_pause: 0
    rx_flow_control_unsupported: 0
    tx_tco_packets: 0
    rx_tco_packets: 0

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    0 Votes
    marty_dunne

    Hello Mark
    I have installed and configured a third NIC (in both positions)but no change.

    I have examined the corrupt files and they are only a few bytes smaller than the original good files.

    I used a network scanner to view activity on both NIC's. It appears that some information is lost at the very end of the email attachment transfer.


    I hope this helps.

    Thanks for all help
    Martin

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    0 Votes
    markp24

    yes definitly does, , I am just stumped as to what though, so we have verified that the isp router tests good (by having a client pc connected directly to that.
    we have confirmed the NIC (s) in the server are good
    we have also confirmed the wiring is good.
    we have disabled the antivirus, spam filters, and firewalls.

    have we confirmed the router is good? (if there is one)


    im thinking what else we can look at.

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    0 Votes
    marty_dunne

    Hello Mark,

    I hope all is well. Getting back to the mail subject -- all is sorted.
    After exhaustive checks, tests, uploads, downloads, NIC scanning and even trying
    a replacement test server, I have found the problem to be our onsite Netopia router (as you mentioned in your last post). Even thought the router appeared to work perfectly when not connected to the Windows 2008 server it did not communicate correctly between our server and the ISP linux mail server when signing off after mail delivery.
    I replaced the router with a modern Netgear router, configured and set it up and all
    mail is arriving fine.
    It would appear that an installed update, either in our server or the Linux mail server
    upset the communications with our mail.
    Thankfully all is working now ( what a nightmare)

    Thanks for all your help (you were the only person to reply with any ideas, in this and
    other forums).

    Thanks again and speak soon.
    Martin

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    0 Votes
    markp24

    Thank you very much :-)

    definitly glad here its now working !!
    feel free to vote or mark the port as selected answer.

    hope to help again one day.
    Robo dev and Col and the other guys are very good too, I guess i just beat them to answering this question LOL

  • +
    0 Votes
    robo_dev

    If so, what version of exchange?

    You stated:
    "If I bypass the server and connect a PC directly to our router all mail received is perfect"

    That would imply that you have no mail server? Or are you using Exchange to simply forward email?

    +
    0 Votes
    markp24

    is it possible one of the Nics went bad or maybe you need change the nic setting from auto/auto to 100/full., maybe the nic driver, or the ethernet cable?

    just thoughts.

    +
    0 Votes
    marty_dunne

    Yes you are correct, we have no exchange server on site, not enough clients to merit.
    There are 4 companies sharing the building network infrastructure so our server acts
    to firewall and isolate our network segment from the rest.
    All emails are accessed directly from isp mail server externally, through our server,
    to each internal client.
    I have checked and replaced all cables but no change.
    Everything else works fine i.e web access/ftp/outgoing mail/server file sharing etc except incoming mail attachments are corrupt (some get through ok).

    thanks for all replies
    Martin

    +
    0 Votes
    roxy786

    Which AV are you using?
    Check with Email Filter option and Level of Security applied to it..

    +
    0 Votes
    markp24

    hmm this one is a stumper. have you tired checking for packet retransmits on the network, (using a sniffer or drom the router logs) I have rebooted a server uning a linux live cd and went to a terminal and typed "ethtool -S eth0"
    (etho may vary) and it shows a chart with all kinds of great info , but i found i had a nic that was retransmitteding packets due to it being set to auto/auto for the duplex setting (i ended up having to set it to 100/full and the same on the cisco port, seems the negotiation protocols arent 100% perfect).
    everythingworked fin on the server except for when i tried to copy a large file, i would get network resource no longer avaiable in windows . so i wonder if this is similar to your issue. (worth a look)
    not sure how to get the same in windows without a deticated diag tool for that Nic or maybe using a sniffer.

    but heres a sample for the linux command output

    NIC statistics:
    rx_packets: 1669993
    tx_packets: 627631
    rx_bytes: 361714034
    tx_bytes: 88228145
    rx_errors: 0
    tx_errors: 0
    rx_dropped: 0
    tx_dropped: 0
    multicast: 0
    collisions: 0
    rx_length_errors: 0
    rx_over_errors: 0
    rx_crc_errors: 0
    rx_frame_errors: 0
    rx_fifo_errors: 0
    rx_missed_errors: 0
    tx_aborted_errors: 0
    tx_carrier_errors: 0
    tx_fifo_errors: 0
    tx_heartbeat_errors: 0
    tx_window_errors: 0
    tx_deferred: 0
    tx_single_collisions: 0
    tx_multi_collisions: 0
    tx_flow_control_pause: 0
    rx_flow_control_pause: 0
    rx_flow_control_unsupported: 0
    tx_tco_packets: 0
    rx_tco_packets: 0

    +
    0 Votes
    marty_dunne

    Hello Mark
    I have installed and configured a third NIC (in both positions)but no change.

    I have examined the corrupt files and they are only a few bytes smaller than the original good files.

    I used a network scanner to view activity on both NIC's. It appears that some information is lost at the very end of the email attachment transfer.


    I hope this helps.

    Thanks for all help
    Martin

    +
    0 Votes
    markp24

    yes definitly does, , I am just stumped as to what though, so we have verified that the isp router tests good (by having a client pc connected directly to that.
    we have confirmed the NIC (s) in the server are good
    we have also confirmed the wiring is good.
    we have disabled the antivirus, spam filters, and firewalls.

    have we confirmed the router is good? (if there is one)


    im thinking what else we can look at.

    +
    0 Votes
    marty_dunne

    Hello Mark,

    I hope all is well. Getting back to the mail subject -- all is sorted.
    After exhaustive checks, tests, uploads, downloads, NIC scanning and even trying
    a replacement test server, I have found the problem to be our onsite Netopia router (as you mentioned in your last post). Even thought the router appeared to work perfectly when not connected to the Windows 2008 server it did not communicate correctly between our server and the ISP linux mail server when signing off after mail delivery.
    I replaced the router with a modern Netgear router, configured and set it up and all
    mail is arriving fine.
    It would appear that an installed update, either in our server or the Linux mail server
    upset the communications with our mail.
    Thankfully all is working now ( what a nightmare)

    Thanks for all your help (you were the only person to reply with any ideas, in this and
    other forums).

    Thanks again and speak soon.
    Martin

    +
    0 Votes
    markp24

    Thank you very much :-)

    definitly glad here its now working !!
    feel free to vote or mark the port as selected answer.

    hope to help again one day.
    Robo dev and Col and the other guys are very good too, I guess i just beat them to answering this question LOL