SMTP SSH Tunneling (Port Forwarding)

ASP: SMTP SSH Tunneling (Port Forwarding) SQL Server: SMTP SSH Tunneling (Port Forwarding) C#: SMTP SSH Tunneling (Port Forwarding) C++: SMTP SSH Tunneling (Port Forwarding) MFC: SMTP SSH Tunneling (Port Forwarding) C: SMTP SSH Tunneling (Port Forwarding) Delphi: SMTP SSH Tunneling (Port Forwarding) Visual FoxPro: SMTP SSH Tunneling (Port Forwarding) Java: SMTP SSH Tunneling (Port Forwarding) Perl: SMTP SSH Tunneling […]

Mail not sent when SendEmail returns success?

Question: Looks to me like sendmail is returning true before the message has been sent but I’m sure you’ll tell me that there is no way this can happen… Answer: The SendEmail method returned true after the email was successfully handed over to the SMTP server. When the SMTP server decides to actually forward the email onward to its destination […]

421 #4.4.5 Too many connections from your host

Question: I get this error from my SMTP server: 421 #4.4.5 Too many connections from your host What does it mean? Answer: The “too many connections from your host” error is the text of the error message that is coming back from the SMTP server. It indicates that the SMTP server has a limit on how many simultaneous open connections […]

POP3 and SMTP multithread-safe?

Question: Is your component fully threadable? Is it thread safe to use in a multithreaded application? Does it Supports multiple (simultaneous) connections? Answer: Yes, it’s safe for multi-threading. However, you cannot have several threads all trying to share the same POP3 or SMTP session at the same time because they would all interfere with each other — for example, one […]

SMTP Protocol (in a Nutshell)

Question: SendMime requires a from  and  recipients address string, but the MIME message contains both .  The message I receive from the SendMime seems to ignore the addresses in the call and uses the one in the MIME.  So why require a from and recipient address? Answer: The SMTP protocol works like this: 1) A client connects to an SMTP […]

Port 465 is Normally the Implicit SSL SMTP Port, but not always…

If you open a DOS prompt and telnet to an SMTP server (typically port 25 for non-SSL, port 465 for SSL), you should get a human-readable printable-text “HELLO” message from the non-SSL port, but binary SSL-handshake protocol gobbly-gook from an implicit SSL port. For example: > telnet mail.chilkatsoft.com 25 220 mail.chilkatsoft.com ESMTP MailEnable Service, Version: 0-1.85- ready at 05/30/08 08:04:19 […]

Service Extension for Delivery Status Notifications (DSNs)

Chilkat’s email component supports the SMTP DSN extensions (RFC 3461). The MailMan object includes these properties specific to RFC 3461: DsnEnvid: (An SMTP DSN service extension feature) An arbitrary string that will be used as the ENVID property when sending email. See RFC 3461 for more details. DsnNotify: (An SMTP DSN service extension feature) A string that will be used […]

SMTP 550 No such user here

This was just discovered with one SMTP server: the error message: RCPT TO: <somebody@somewhere.com> 550 <somebody@somewhere.com> No such user here Was caused by forgetting to authenticate with the SMTP server.  The SMTP server requires authentication in order to relay email to another domain (in other words, it’s protected against being an open-relay).  The error message from this particular SMTP server […]