It's possible that the smtp server is configured to only allow relay from specific ip addresses. If the sites have different ip addresses then perhaps one is not allowed to relay.

Hope it helps,

Joe

But do both sites use the same ip address or not?

That is not what I asked. I get it that they are on the same machine but the machine may have multiple ip addresses and sites may use the same or different ones and the local smtp configuration may allow only specific ip addresses to relay. So one site may be using an ip address allowed to relay and another site may not.

make sure that in your smtp server configuration, the public ip address of the server is allowed to relay. Note that if the smtp server runs on localhost (which resolves to 127.0.0.1), the public ip address is not seen as local from the perspective of the smtp server, its a remote address. It doesn't know that ip is on the same machine.

Is it possible that in the site where email does not work that you have those settings in more than one place?

ie, if you put the smtp settings from appSettings in a user.config file it will override the settings in Web.config. Also if those settings are listed multiple times in user.config, the settings closer to the bottom of the file will override the settings above.

Hope it helps,

Joe

How do you access the sites, using public urls or localhost?

I think you are not understanding my advice.

On all machines localhost resolves to the loopback address 127.0.0.1.

So a site running at localhost is local to the smtp server running as localhost. Any other url is going to resolve to the public ip address of the server which is not local so the public ip address must explicitly be allowed to relay or the local smtp server will reject it.

Go into IIS right click your smtp server and review properties to make sure the public ip address is listed as allowed to relay.

You may also want to look for errors in the mojoportal log on the site that can't send email. Administration > System Log

Hope it helps,

Joe