Hello, When one of my sites sends messages with certain attachments, communication between the client and the mailserver freezes up, and I am having trouble pinpointing the source. The problem brings up some other questions I have about extended SMTP transmissions that aren't spelled out in RFC 1869. When users at a remote site ("BadSite") try to send mail with certain attachments through our server (or any other server for that matter), the connection gets dropped mid transmission. I notice in the verbose sendmail logs that an ehlo is given, headers are sent, then the mime encoded MSWord doc starts to go through, but in the middle of the transmission the client appears to just sit until the connection times out. We get a "read error" in Sendmail, and a time-out error in Outlook. The same thing happens when using 'mutt' in Linux. Things I've noticed: * Problem is isolated to BadSite...They cannot send these attachments through my server, or anyone else's for that matter. * Some attachments go through just fine... .jpg, .pdf, .bmp and .txt work OK. If you change the extension of a good file to .doc, it goes through just fine (it's not like the extension alone is causing the problem). :) * An EHLO is given when sending files like .doc and others that FAIL, while HELO is offered every time the good files go through. ESMTP connections from any other lan work fine on my server. Mail clients at BadSite range from MSOutlook on NT, to mutt on Linux boxes. We have a Cisco router with no access-lists on it and no firewall. Is this a problem with the type of transmission (ESMTP vs SMTP)? Encapsulation? It doesn't seem like a server problem, but I was told it couldn't possibly be a router problem....not sure where to go from here. Another question: What determines whether a client sends EHLO or HELO? Thanks for your input! Joe Arnstein <clips from logs follow> 28803 >>> 220 mail.mymailserver.com ESMTP 28803 <<< EHLO client.mylan.com 28803 >>> 250-mail.mymailserver.com Hello client.mylan.com [63.75.xx.xxx], pleased to meet you 28803 >>> 250-8BITMIME 28803 >>> 250-SIZE 28803 >>> 250-DSN 28803 >>> 250-ONEX 28803 >>> 250-XUSR 28803 >>> 250 HELP 28803 <<< MAIL From:<root@client.mylan.com> SIZE=15045 28804 >>> 250 <root@client.mylan.com>... Sender ok 28804 <<< RCPT To:<whomever@anydomain.com> 28804 >>> 250 <whoever@anydomain.com>... Recipient ok 28804 <<< DATA 28804 >>> 354 Enter mail, end with "." on a line by itself 28804 <<< Received: (from root@localhost) 28804 <<< by client.mylan.com (8.9.3/8.9.3) id PAA12375 28804 <<< for whomever@anydomain.com; Tue, 20 Feb 2001 15:52:35 -0500 28804 <<< Date: Tue, 20 Feb 2001 15:52:35 -0500 28804 <<< From: localuser <root@client.mylan.com> 28804 <<< To: whomever@anydomain.com 28804 <<< Subject: here we go again 28804 <<< Message-ID: <20010220155235.A12365@client.mylan.com> 28804 <<< Mime-Version: 1.0 28804 <<< Content-Type: multipart/mixed; boundary="n8g4imXOkfNTN/H1" 28804 <<< X-Mailer: Mutt 0.95.4us 28804 <<< 28804 <<< 28804 <<< --n8g4imXOkfNTN/H1 28804 <<< Content-Type: text/plain; charset=us-ascii 28804 <<< 28804 <<< content of message.... 28804 <<< 28804 <<< --n8g4imXOkfNTN/H1 28804 <<< Content-Type: application/msword 28804 <<< Content-Disposition: attachment; filename="Document.doc" 28804 <<< Content-Transfer-Encoding: base64 28804 <<< 28804 <<< 0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAAAAAABAAAAEQAAAAAA 28804 <<< AAAAEAAAEgAAAAEAAAD+////AAAAABAAAAD///////////////////////////////////// 28804 <<< //////////////////////////////////////////////////////////////////////// 28804 <<< //////////////////////////////////////////////////////////////////////// 28804 <<< //////////////////////////////////////////////////////////////////////// 28804 <<< //////////////////////////////////////////////////////////////////////// 28804 <<< //////////////////////////////////////////////////////////////////////// 28804 <<< //////////////////////////////////////////////////////////////////////// 28804 <<< //////////////////////////////////////////////////////////////////////// 28804 <<< ///////////////////////////////////spcAARQAJBAAAABK/AAAAAAAAEgAAAAAABAAA 28804 <<< AQQAAA4AYmpiakLgQuAAAAAAAAAAAAAAAAAAAAAAAAAJBBYAHgwAACCKAQAgigEAAQAAAAAA 28804 <<< AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAD//w8AAAAAAAAAAAD//w8AAAAAAAAAAAD//w8A 28804 <<< AAAAAAAAAAAAAAAAAAAAAF0AAAAAAFwBAAAAAAAAXAEAAFwBAAAAAAAAXAEAAAAAAABcAQAA 28804 <<< AAAAAFwBAAAAAAAAXAEAABQAAAAAAAAAAAAAAHABAAAAAAAAcAEAAAAAAABwAQAAAAAAAHAB 28804 <<< AAAAAAAAcAEAAAwAAAB8AQAADAAAAHABAAAAAAAAQwIAALYAAACUAQAAAAAAAJQBAAAAAAAA 28804 <<< lAEAAAAAAACUAQAAAAAAAJQBAAAAAAAAlAEAAAAAAACUAQAAAAAAAJQBAAAAAAAACAIAAAIA 28804 <<< AAAKAgAAAAAAAAoCAAAAAAAACgIAAAAAAAAKAgAAAAAAAAoCAAAAAAAACgIAACQAAAD5AgAA 28804 <<< 9AEAAO0EAABmAAAALgIAABUAAAAAAAAAAAAAAAAAAAAAAAAAXAEAAAAAAACUAQAAAAAAAAAA 28804 <<< AAAAAAAAAAAAAAAAAACUAQAAAAAAAJQBAAAAAAAAlAEAAAAAAACUAQAAAAAAAC4CAAAAAAAA 28804 <<< qAEAAAAAAABcAQAAAAAAAFwBAAAAAAAAlAEAAAAAAAAAAAAAAAAAAJQBAAAAAAAAlAEAAAAA 28804 <<< AACoAQAAAAAAAKgBAAAAAAAAqAEAAAAAAACUAQAACgAAAFwBAAAAAAAAlAEAAAAAAABcAQAA 28804 <<< AAAAAJQBAAAAAAAACAIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAcAEAAAAAAABwAQAAAAAAAFwB 28804 <<< AAAAAAAAXAEAAAAAAABcAQAAAAAAAFwBAAAAAAAAlAEAAAAAAAAIAgAAAAAAAKgBAABgAAAA 28804 <<< qAEAAAAAAAAAAAAAAAAAAAgCAAAAAAAAXAEAAAAAAABcAQAAAAAAAAAAAAAAAAAAAAAAAAAA 28804 <<< AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAIAAAAAAACUAQAA 28804 <<< AAAAAIgBAAAMAAAAcABqZPK2uwFwAQAAAAAAAHABAAAAAAAAngEAAAoAAAAIAgAAAAAAAAAA 28804 <<< AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA 28804 <<< AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA <at this point transmission hangs and connection eventually drops>