Using JavaMail, when sending a message, how can i tell if SMTP server is down?
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Posted By:   Aleksandr_Shneyder
Posted On:   Saturday, November 29, 2003 09:43 AM

This is pretty much my question.

Thanks,

Alex

Re: Using JavaMail, when sending a message, how can i tell if SMTP server is down?

Posted By:   Christopher_Koenigsberg  
Posted On:   Saturday, November 29, 2003 12:56 PM

Presumably (? RTFJD) your connection attempts will fail and/or throw a MessagingException. (e.g. as opposed to failures due to authentication)


But remember that you are writing tcp/ip networking code, regardless of how an API tries to simplify it for you.


A failed esmtp/smtp connection, just like any other tcp connection attempt that fails, could be for various different reasons, including: server host is up on the network (e.g. pingable, traceroutable, maybe reachable by other protocols) but no service daemon is listening on that specific port (e.g. tcp 25); entire server host is down temporarily (would be reachable if you try again in a few minutes, hours, or days); server host is down permanently (you need to find yourself a different server host); network/routing/firewall problem between you and the host -- maybe the host is up and is listening on port 25, if your packets could only get to it; or maybe your packets get to it, but the return packets can't get back to you --, etc. (if you are referring to the server by a hostname, there could be temporary or permanent DNS issues too, e.g. it might even be reachable via its IP address, in the meantime until someone fixes a DNS server you are trying ...)

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