SMTP Relay

[bossman]

Scenario:

 

We have migrated over to Gsuite and in the first instance removed our old but efficient local Zimbra e-mail server, everything went well and the Staff and students are well impressed with Gsuite, only problem I have is that two of our other services which used the Zimbra MTA as mail relay mainly our helpdesk (Liberum customised) and AnyComms (MIS app for secure transport of files to and from the LA).

 

I have setup SMTP relay on one of our servers using IIS.6.0 Virtual SMTP server, I have tested this rigorously using both Telnet and dropping a text e-mail file into the Pickup box in the mailroot folder and checking the email account that it has been sent to and from which works 100%, I can get the reports up from within the Gsuite admin console which confirms this.

 

The 2 apps are configured to use the SMTP relay but, and here is the quandry, they fail to use the SMTP although they are pointed at the SMTP in their config files the same as when we used the Zimbra email server (IP address of the SMTP server).

 

My thinking is that the SMTP server is denying these apps access but why? Where would I find out?

 

Reason for using local mail relay is that both these apps would not be able to use a remote SMTP Relay as defined in their help files.

 

Please will someone help me out here as I think I'm going mad

 

Thank you in advance

[pcstru]

You can telnet to an SMTP port and inject mail via a terminal. That may help diagnose what the issue is (and where it is occurring).

[bossman]

@pcstru

 

Thanks but I've already done that and I cannot find anything in the event logs which determine what is happening!

 

Its a real mystery as both these apps were working perfectly using our Zimbra mail server as the relay

[dhicks]

My thinking is that the SMTP server is denying these apps access but why?

 

I know on our Exchange 2010 server we have to explicitly allow specific internal IP addresses to be able to connect via SMTP and send emails. In Exchange 2010 that's done with a Receive Connector (I think), there might be an equivalent in your SMTP Relay server settings.

[bossman]

@dhicks

 

Yes I have already configured this both in the inbound and outbound part of the SMTP relay to allow both addresses of the servers where these apps are installed,

 

thank you all the same for taking timeout to reply appreciated

[pcstru]

@pcstru

Thanks but I've already done that and I cannot find anything in the event logs which determine what is happening!

Its a real mystery as both these apps were working perfectly using our Zimbra mail server as the relay

When you did it, you manually injected a mail and got a 250 (Requested mail action okay, completed) response? Did you telnet from the machine that is trying to relay (i.e. did you have the same IP etc).

 

In the absence of good logs, I think to make progress I'd either packet sniff the outgoing connection from the relay (assuming mail is getting into the relay, is it trying to get out) or use a proxy to capture traffic and look at those conversations.

[Domino]

as you're restricting by IP have you checked anonymous access is enabled as mentioned here: https://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/58f05ef9-55a3-42b3-9f57-27fdc8723b8a.mspx?mfr=true

[limawhiskey]

This doesn't solve your particular problem but may be a workaround for you:

 

I have set up a 'service' user and I use these credentials to log in to Google's secure SMTP send mail for similar services. You could use the same technique to get your mail delivery going again. I just put that user in an OU with permissions for SMTP access and allowed port 993 through the firewall for the devices that need access.

 

Sorry, I can't help with trouble shooting your mail relay - I didn't have the skills to set this up when we migrated to G Suite!

[bossman]

Update:

 

For some unknown reason the AnyComms app has started working! Truly amazing! hehe! IT at its real best haha!

 

Still have the other app to sort but at least I know the whole process works!

 

Thank you all for your replies and I will update on the other app when I have sorted it, cheers and have a great day all of you

[bossman]

Hi Guy's,

 

Update:

 

Our Helpdesk and all the other legacy apps requiring email correspondence I have managed to sort, setup SMTP relay on 2 member 2012R2 servers and used a little known asp mail client (ASPEmail) to relay mail from these to the SMTP relays and bingo!!! all is well in the garden now,

 

Thanks to all you guy's who offered sound advice, appreciated