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dotnet framework : SmtpMail connection question.
written in C# and uses the SmtpMail class. The other is in C++ and uses the ATL CSMTPConnction class. The SmtpMail code works just fine. The CSMTPConnection code fails. In digging down into the ATL code, I can see where it issues a "HELO" command to the smtp server and reads the result to check for a "250" return code as an indicator of success. Using telnet, I can verify that 250 is returned from a "HELO" command. The big wrinkle here is that the smtp server is using a 3rd party smtp security product. I suspect that the ATL code is doing something that the 3rd party product does not like. So, finally, my question is about how the SmtpMail class is successful. Does the underlying code issue a "HELO" command at all?
Unfortunately, I do not have access to the SMTP server, so I am having to
deduce all of this from logging information. I do know that the the failing code is returning FALSE from AtlSmtpSendAndCheck(...) which could be returning false from calls to either AtlSmtpSendAndWait(...) which uses WriteFile() to write "HELO [hostname]" to the socket handle or AtlSmtpReadData(...) which uses ReadFile() to get the response and check for the "250" code in the first 3 characters. Since I don't have access to the SMTP server, I was hoping to deduce what the problem could be based on the fact that the SmtpMail class had no problem at all using the same server. FYI - When using telnet to check the response to "HELO", the response is the following ( "xxxxx" for the brand of the proxy & replaced hostnames as well ). 220-xxxxxx SMTP proxy 220 a.b.c ESMTP server ready at Thu, 4 May 2006 09:47:35 +0200 helo myclient 250 a.b.c Hello localhost [127.0.0.1], pleased to meet you The "Hello localhost [127.0.0.1]" jumped out at me since I expected the IP address of the calling client. However, that doesn't explain why the SMTPMail class works. Sorry I can't provide any better info. Your comments are much appreciated! [quoted text, click to view] "Ben Voigt" wrote:
> Every SMTP connection needs to start with either HELO or EHLO (extended > HeLOo). > > But then it's going to possibly start SSL (in which case Ethereal won't help > much) and then go on with "MAIL FROM: sender" and "RCPT TO: recipient" > (possibly multiple times) then "DATA" followed by the MIME wrapped message > and then a period "." on a line by itself which will go back to command > mode. > > http://cr.yp.to/smtp/mail.html > > "Kevin Spencer" <kevin@DIESPAMMERSDIEtakempis.com> wrote in message > news:%23CTMcOHcGHA.1276@TK2MSFTNGP03.phx.gbl... > > Can you monitor both sides of the conversation? That is, using Ethereal > > (free from Ethereal.com), or some other packet sniffer, check the entire > > conversation, both client and server. > > > > -- > > HTH, > > > > Kevin Spencer > > Microsoft MVP > > Professional Numbskull > > > > Hard work is a medication for which > > there is no placebo. > > > > "Mitch" <Mitch@discussions.microsoft.com> wrote in message > > news:9A7DFFB0-2D90-48DC-AF97-F3E91A858A19@microsoft.com... > >> I've got 2 different applications that use the same SMTP server. One is > >> written in C# and uses the SmtpMail class. The other is in C++ and uses > >> the > >> ATL CSMTPConnction class. The SmtpMail code works just fine. The > >> CSMTPConnection code fails. In digging down into the ATL code, I can see > >> where it issues a "HELO" command to the smtp server and reads the result > >> to > >> check for a "250" return code as an indicator of success. Using telnet, > >> I > >> can verify that 250 is returned from a "HELO" command. The big wrinkle > >> here > >> is that the smtp server is using a 3rd party smtp security product. I > >> suspect that the ATL code is doing something that the 3rd party product > >> does > >> not like. So, finally, my question is about how the SmtpMail class is > >> successful. Does the underlying code issue a "HELO" command at all? > >> > >> TIA - Mitch > > > > > >
Every SMTP connection needs to start with either HELO or EHLO (extended
HeLOo). But then it's going to possibly start SSL (in which case Ethereal won't help much) and then go on with "MAIL FROM: sender" and "RCPT TO: recipient" (possibly multiple times) then "DATA" followed by the MIME wrapped message and then a period "." on a line by itself which will go back to command mode. http://cr.yp.to/smtp/mail.html [quoted text, click to view] "Kevin Spencer" <kevin@DIESPAMMERSDIEtakempis.com> wrote in message news:%23CTMcOHcGHA.1276@TK2MSFTNGP03.phx.gbl... > Can you monitor both sides of the conversation? That is, using Ethereal > (free from Ethereal.com), or some other packet sniffer, check the entire > conversation, both client and server. > > -- > HTH, > > Kevin Spencer > Microsoft MVP > Professional Numbskull > > Hard work is a medication for which > there is no placebo. > > "Mitch" <Mitch@discussions.microsoft.com> wrote in message > news:9A7DFFB0-2D90-48DC-AF97-F3E91A858A19@microsoft.com... >> I've got 2 different applications that use the same SMTP server. One is >> written in C# and uses the SmtpMail class. The other is in C++ and uses >> the >> ATL CSMTPConnction class. The SmtpMail code works just fine. The >> CSMTPConnection code fails. In digging down into the ATL code, I can see >> where it issues a "HELO" command to the smtp server and reads the result >> to >> check for a "250" return code as an indicator of success. Using telnet, >> I >> can verify that 250 is returned from a "HELO" command. The big wrinkle >> here >> is that the smtp server is using a 3rd party smtp security product. I >> suspect that the ATL code is doing something that the 3rd party product >> does >> not like. So, finally, my question is about how the SmtpMail class is >> successful. Does the underlying code issue a "HELO" command at all? >> >> TIA - Mitch > >
Can you monitor both sides of the conversation? That is, using Ethereal
(free from Ethereal.com), or some other packet sniffer, check the entire conversation, both client and server. -- HTH, Kevin Spencer Microsoft MVP Professional Numbskull Hard work is a medication for which there is no placebo. [quoted text, click to view] "Mitch" <Mitch@discussions.microsoft.com> wrote in message news:9A7DFFB0-2D90-48DC-AF97-F3E91A858A19@microsoft.com... > I've got 2 different applications that use the same SMTP server. One is > written in C# and uses the SmtpMail class. The other is in C++ and uses > the > ATL CSMTPConnction class. The SmtpMail code works just fine. The > CSMTPConnection code fails. In digging down into the ATL code, I can see > where it issues a "HELO" command to the smtp server and reads the result > to > check for a "250" return code as an indicator of success. Using telnet, I > can verify that 250 is returned from a "HELO" command. The big wrinkle > here > is that the smtp server is using a 3rd party smtp security product. I > suspect that the ATL code is doing something that the 3rd party product > does > not like. So, finally, my question is about how the SmtpMail class is > successful. Does the underlying code issue a "HELO" command at all? > > TIA - Mitch
It is possible the SMTP is setup to use Extended HELO instead of the basic
implementation. This is actually fairly common. By switching to EHLO, your mail will start again. This should not be a major undertaking, but it could add a bit of work to your plate. -- Gregory A. Beamer ************************************************* Think Outside the Box! ************************************************* [quoted text, click to view] "Mitch" <Mitch@discussions.microsoft.com> wrote in message news:9A7DFFB0-2D90-48DC-AF97-F3E91A858A19@microsoft.com... > I've got 2 different applications that use the same SMTP server. One is > written in C# and uses the SmtpMail class. The other is in C++ and uses > the > ATL CSMTPConnction class. The SmtpMail code works just fine. The > CSMTPConnection code fails. In digging down into the ATL code, I can see > where it issues a "HELO" command to the smtp server and reads the result > to > check for a "250" return code as an indicator of success. Using telnet, I > can verify that 250 is returned from a "HELO" command. The big wrinkle > here > is that the smtp server is using a 3rd party smtp security product. I > suspect that the ATL code is doing something that the 3rd party product > does > not like. So, finally, my question is about how the SmtpMail class is > successful. Does the underlying code issue a "HELO" command at all? > > TIA - Mitch
[quoted text, click to view]
> Unfortunately, I do not have access to the SMTP server, so I am having to > deduce all of this from logging information. I do know that the the > failing > code is returning Remember that a network connection is like a phone call. You don't have to be on both ends to hear both sides of the conversation. If you put a packet sniffer on the client, it will hear both sides on the client end. I have found Ethereal to be priceless (literally, in fact!) for debugging networked applications. -- HTH, Kevin Spencer Microsoft MVP Professional Numbskull Hard work is a medication for which there is no placebo. [quoted text, click to view] "Mitch" <Mitch@discussions.microsoft.com> wrote in message news:D18D8235-47AD-4CE5-8B72-4C0709E6B375@microsoft.com... > Unfortunately, I do not have access to the SMTP server, so I am having to > deduce all of this from logging information. I do know that the the > failing > code is returning > FALSE from AtlSmtpSendAndCheck(...) which could be returning false from > calls to either AtlSmtpSendAndWait(...) which uses WriteFile() to write > "HELO > [hostname]" to the socket handle or AtlSmtpReadData(...) which uses > ReadFile() to get the response and check for the "250" code in the first 3 > characters. Since I don't have access to the SMTP server, I was hoping to > deduce what the problem could be based on the fact that the SmtpMail class > had no problem at all using the same server. > > FYI - When using telnet to check the response to "HELO", the response is > the > following ( "xxxxx" for the brand of the proxy & replaced hostnames as > well ). > > 220-xxxxxx SMTP proxy > 220 a.b.c ESMTP server ready at Thu, 4 May 2006 09:47:35 +0200 > helo myclient > 250 a.b.c Hello localhost [127.0.0.1], pleased to meet you > > The "Hello localhost [127.0.0.1]" jumped out at me since I expected the IP > address of the calling client. However, that doesn't explain why the > SMTPMail > class works. > > Sorry I can't provide any better info. Your comments are much > appreciated! > > "Ben Voigt" wrote: > >> Every SMTP connection needs to start with either HELO or EHLO (extended >> HeLOo). >> >> But then it's going to possibly start SSL (in which case Ethereal won't >> help >> much) and then go on with "MAIL FROM: sender" and "RCPT TO: recipient" >> (possibly multiple times) then "DATA" followed by the MIME wrapped >> message >> and then a period "." on a line by itself which will go back to command >> mode. >> >> http://cr.yp.to/smtp/mail.html >> >> "Kevin Spencer" <kevin@DIESPAMMERSDIEtakempis.com> wrote in message >> news:%23CTMcOHcGHA.1276@TK2MSFTNGP03.phx.gbl... >> > Can you monitor both sides of the conversation? That is, using Ethereal >> > (free from Ethereal.com), or some other packet sniffer, check the >> > entire >> > conversation, both client and server. >> > >> > -- >> > HTH, >> > >> > Kevin Spencer >> > Microsoft MVP >> > Professional Numbskull >> > >> > Hard work is a medication for which >> > there is no placebo. >> > >> > "Mitch" <Mitch@discussions.microsoft.com> wrote in message >> > news:9A7DFFB0-2D90-48DC-AF97-F3E91A858A19@microsoft.com... >> >> I've got 2 different applications that use the same SMTP server. One >> >> is >> >> written in C# and uses the SmtpMail class. The other is in C++ and >> >> uses >> >> the >> >> ATL CSMTPConnction class. The SmtpMail code works just fine. The >> >> CSMTPConnection code fails. In digging down into the ATL code, I can >> >> see >> >> where it issues a "HELO" command to the smtp server and reads the >> >> result >> >> to >> >> check for a "250" return code as an indicator of success. Using >> >> telnet, >> >> I >> >> can verify that 250 is returned from a "HELO" command. The big >> >> wrinkle >> >> here >> >> is that the smtp server is using a 3rd party smtp security product. I >> >> suspect that the ATL code is doing something that the 3rd party >> >> product >> >> does >> >> not like. So, finally, my question is about how the SmtpMail class is >> >> successful. Does the underlying code issue a "HELO" command at all? >> >> >> >> TIA - Mitch >> > >> > >> >> >>
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