Kishore> Thank you for the reply. Actually it was setup like this by Kishore> another member, who left the team/ company recently. Now it Kishore> came to me to handle that responsibility. That's how I got in Kishore> to this. At present I am not able to migrate/upgrade Kishore> immediately. Because it sends emails around 100K+ emails Kishore> everyday and I do not want to disturb that.
Dovecot doesn't do *any* mailing, that's handled by postfix or sendmail or qmail. I think postfix is the best. You can run your outgoing email on a seperate server without any problems.
Kishore> Coming back to your question, Actually the connection is :
Kishore> O365/Outlook >> SMTP Gateway Server >> testing.test.com >> 2 POP3 servers.
Why are you running POP3 in this day and age? Wait, don't answer that. :-)
Kishore> Actually "testing.test.com", that is FQDN name set in F5 Kishore> load balancer, where it is having the 2 POP3 servers to route Kishore> the emails.
By POP3, I assume you mean the two dovecot servers?
Kishore> When the email was sent from Outlook/O365, first it goes to Kishore> SMTP Gateway Server. Now the SMTP Gateway server has the Kishore> postfix rule to send it to "testing.test.com". In this Kishore> location, I am getting the error in SMTP Gateway Server, Kishore> where it is not able connect ( lost connection with Kishore> testing.test.com [xxx.xxx.xxx.xxx] while receiving the Kishore> initial server greeting).
What is the gateway server and how is it configured to deliver the mail to the backend servers?
Kishore> In SMTP Gateway server, instead of "testing.test.com", if i Kishore> give the name/ip of any POP3 server, then email delivery is Kishore> happening successfully to that POP3 server. The above error Kishore> is coming only when i use the fqdn "testing.test.com", Kishore> instead of direct POP3 server.
This is because your two backend servers probably don't know how to accept email for the testing.test.com domain IP/name. Again, this sounds like a mailing problem, not a dovecot problem.
You need to provide lots of details here. And ideally the logs from both the SMTP gateway, and the two backend servers, along with full details of how they are configured.
But from what I see here, this is a mail configuration problem, not a dovecot issue. But you don't give enough details.
Kishore> Please let me know if you need any more details. Could you please help me here.
Kishore> On Thu, Apr 23, 2020 at 7:13 PM John Stoffel john@stoffel.org wrote:
"Kishore" == Kishore Potnuru kishore.reachme@gmail.com writes:
Kishore> I have the dovecot version 2.0.9 installed on RHEL linux 6.10 Kishore> version. It's a single/standalone Live server.
Kishore> You should really upgradr your setup.
Kishore> Now I have created another server with the same configuration Kishore> for the resilince purpose. I also tested and I am able to Kishore> send the emails to both of the dovecot servers Kishore> separately/individually. They are working fine.
Kishore> Dovecot doesn't do the mailing between systems, so i assume you've got Kishore> postfix configured? And do you have shared storage behind your two Kishore> dovecot instances so that your users don't have to login to multiple Kishore> systems to get emails?
Kishore> Did you read the docs at:
Kishore> https://doc.dovecot.org/admin_manual/dovecot_cluster_architecture/
Kishore> Now I have added those two servers under a F5 load balancer Kishore> and created a FQDN (example: testing.test.com). I changed the Kishore> rules to send the traffic to FQDN "testing.test.com", where Kishore> it should redirect the email to one of those 2 servers.
Kishore> So how is your F5 configured to work when one server is down?
Kishore> When I sent the email to FQDN "testing.test.com", I am getting the below error.
Kishore> pf1_inbd/smtp[30292]: 66A5F5F6: to=xxxxx@yyy.com, Kishore> relay=testing.test.com[xxx.xxx.xxx.xxx]:25, delay=13, Kishore> delays=0.09/0.08/13/0, dsn=4.4.2, status=deferred (lost Kishore> connection with testing.test.com [xxx.xxx.xxx.xxx] while Kishore> receiving the initial server greeting)
Kishore> Could you please let me know how to fix this issue? It's a great help for me.
Kishore> Sounds like you haven't actually setup your system correctly. But Kishore> we're not going to be able to help until you provide more details. Kishore> It's also not clear from the about log file *which* server gave you Kishore> this error.
Kishore> It would be smarted to start from scratch with an upto date install of Kishore> dovecot (and postfix in my opinion) according to the Dovecot docs Kishore> above, and test that out in a test environment. Then you would use Kishore> 'doveadm' sync to migrate user accounts over to the new system.
Kishore> John