Any software/proxy that can do SMTP failover?

Question

I'm using a monitoring software that sends out email to my ISP's mail server (SMTP Server). But sometimes, the ISP's mail server goes down, or takes too long to respond, I would like to find out if there's a Windows software/proxy that can forward the email to another mail server, e.g. Gmail, Yahoo mail, etc.

Not really a fix for 75% of these cases, but if the destination is hosted with Google (GMail or Google Apps) then you can send the mail to ASPMX.L.GOOGLE.COM. It will only accept non-SSL smtp. It will only deliver to Google Apps or GMail domains. Your mail will have a higher chance of being marked as Spam. The server farm will be as close to 100% available as it's practical to get. — Dom, Sep 05 '13 at 06:07
If SMTP is down, is trying a different server really the best choice? Why not setup XMPP, or SMS as a backup? — Zoredache, Sep 05 '13 at 06:26
@Zoredache Yes, it might also be SMS, many SMS Servers have got an SMTP interface. — Joshua Lim, Sep 05 '13 at 13:58

score 1 · Answer 1 · answered Sep 05 '13 at 06:11

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You can install postfix and set your ISP's mail server as relayhost. If ISP's mail server is busy or down your mail server will try again later.

http://www.howtoforge.com/postfix_relaying_through_another_mailserver

answered Sep 05 '13 at 06:11

Laurentiu Roescu

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+1 for this; if you want SMTP redelivery attemps, a local MTA (properly configured) is the right way to do it. – MadHatter Sep 05 '13 at 06:14
@LaurentiuRoescu Thanks, sorry, I'm looking at a Windows method. I should have pointed that out earlier. :) – Joshua Lim Sep 05 '13 at 14:04
@JoshuaLim You can install a local MTA also on Windows. There are some free options, for example: http://www.hmailserver.com/ – Laurentiu Roescu Sep 05 '13 at 15:23

score 1 · Answer 2 · answered Sep 05 '13 at 06:28

If you want to do things 'right', a local Mail Transfer Agent (MTA) such as Exim or Postfix will handle this easily. This sort of routing decision is what MTAs are designed to do.

If you have in-house expertise around web handling and no local SMTP expertise, then in the interests of using tooling that your folks are likely already familiar with, you can deploy nginx as an SMTP proxy and configure multiple backends.

Any software/proxy that can do SMTP failover?

2 Answers2