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I have set up inbound e-mail in my SAP system and it works fine, however it will not allow me to bind port 25 to more than 1 application server at the same time.

This means that there is 1 point of failure.

How can I bind port 25 to more than 1 application server? Or is there an alternative solution that I should be looking at?


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I'm not sure if this is the answer you are looking for, but could you use different mx records to point to different ip's?

These ips could then be used to route the information where you need it?

Otherwise to avoid the 1 point of failure, maybe you could setup another mail server, which could receive mail as well, and re direct it to the SAP system?

Do you not already have 1 point of failure by having a single server?

Sorry if this doesn't help at all, or I am stating the obvious.


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Not quite the answer I was looking for, but yes the MX records could be one solution :-) – Techboy May 8 '09 at 16:33

You can't bind more then one process (icmp in this case) to tcp port on one IP address. Depending on you system landscape you have several options.

  • Don't worry about single point of failure. The incoming smtp traffic will be retried by the sending server. The icmp process is watched over, and restarted, by the dispatcher. So if its down you probably have more serious problems then the incoming smtp problem.
  • If you have several application servers, then you can just use all of them as smtp hosts. This is done in the instance profile. Then, as optician has noted, you configure the dns with all those ip as mx records. Most of the time you don't want your sap server to be facing the internet directly so this option needs some dns trickery.
  • If you worry about single point of failure, then your central instance must be already clustered. If this is the case. Then the icmp is as robust as any other part in your sap installation.
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I am running a high-availability system so my CI is clustered. I will try binding port 25 to that instead of to the physical instance. You are correct, that would negate the single point of failure. We don't currently have a high level of inbound e-mail traffic (might in the future) so don't currently require SMTP on all of the servers (i.e. for parallel processing). I will try on Monday and then update this post. Thanks for your help :-) – Techboy May 8 '09 at 16:32
up vote 0 down vote accepted

Actually it appears that transaction SMICM only shows the port as being active on the server that you are currently logged onto with the SAP GUI.

If I go to SM51 and log onto another application server, then go to SMICM, it shows port 25 as being active in that server.

So in fact port 25 was bound on all servers, it's just that the screen in transaction SMICM did not reflect this.

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