Dovecot Load balancing - Please Please Please help me
I need your help on my issue very badly.
I have the dovecot version 2.0.9 installed on RHEL linux 6.10 version. It's a single Live server. I need to add a load balancer by adding another server for resilience.
I cannot upgrade the dovecot version at this time as it is a single live server. If something goes wrong, I will be in trouble.
Basically the requirement/issue is:
a) it's a single live dovecot POP3/IMAP server b) people are accessing their emails from microsoft outlook (by giving the same server name as IMAP and SMTP server). But more than 100000 emails will be travelled/routed. c) This server is not rebooted from couple of years. d) Now they are worried about, just in case if the server is having any issues during the reboot or if something goes wrong with the server in any case, there will be huge issues.
e) They would like to create resilience by adding another server and emails will be travelled from both the servers. If one server is having any issues due to any technical issue and if it doesn't come back easily, then the emails will be travelled through the other server and there will no disturbance to the emails. atleast it travels from the other server.
I have very less knowledge on this. Could you please help me providing the best solution for this.
I will wait for your reply. Please please please help me.
Thanks, Kishore Potnuru
Am 16.01.2020 um 18:04 schrieb Kishore Potnuru:
I need your help on my issue very badly.
I have the dovecot version 2.0.9 installed on RHEL linux 6.10 version. It's a single Live server. I need to add a load balancer by adding another server for resilience.
I cannot upgrade the dovecot version at this time as it is a single live server. If something goes wrong, I will be in trouble.
Basically the requirement/issue is:
a) it's a single live dovecot POP3/IMAP server b) people are accessing their emails from microsoft outlook (by giving the same server name as IMAP and SMTP server). But more than 100000 emails will be travelled/routed. c) This server is not rebooted from couple of years. d) Now they are worried about, just in case if the server is having any issues during the reboot or if something goes wrong with the server in any case, there will be huge issues.
e) They would like to create resilience by adding another server and emails will be travelled from both the servers. If one server is having any issues due to any technical issue and if it doesn't come back easily, then the emails will be travelled through the other server and there will no disturbance to the emails. atleast it travels from the other server.
I have very less knowledge on this. Could you please help me providing the best solution for this.
I will wait for your reply. Please please please help me.
Thanks, Kishore Potnuru
Don't take it personal Kishore, you probably just inherited that disaster.
RHEL 6.10 is really old and thus your dovecot version ancient and unsupported by upstream. RHEL 6.10 is going EOL by end of Nov this year. And I am not sure that system is really a clean 6.10 if it hasn't been rebooted since several years as you state.
Load balancing will not solve your issue. Migrate away from that host to a fresh new install with a more current OS and dovecot release. Spin up the new system, configure dovecot properly, sync the mail over from the old system to the new one. Plan a maintenance downtime where you do a final sync and then replace the old host with the new one which you give the same identity. The downtime will be minimal.
Alexander
Hi All,
I need your help on one of the issue in Dovecot.
I have the dovecot version 2.0.9 installed on RHEL linux 6.10 version. It's a single/standalone Live server.
Now I have created another server with the same configuration for the resilince purpose. I also tested and I am able to send the emails to both of the dovecot servers separately/individually. They are working fine.
Now I have added those two servers under a F5 load balancer and created a FQDN (example: testing.test.com). I changed the rules to send the traffic to FQDN "testing.test.com", where it should redirect the email to one of those 2 servers.
When I sent the email to FQDN "testing.test.com", I am getting the below error.
pf1_inbd/smtp[30292]: 66A5F5F6: to=xxxxx@yyy.com, relay=testing.test.com[xxx.xxx.xxx.xxx]:25, delay=13, delays=0.09/0.08/13/0, dsn=4.4.2, status=deferred (lost connection with testing.test.com [xxx.xxx.xxx.xxx] while receiving the initial server greeting)
Could you please let me know how to fix this issue? It's a great help for me.
Thanks & Regards, Kishore Potnuru
Am 22.04.2020 um 15:12 schrieb Kishore Potnuru:
Hi All,
I need your help on one of the issue in Dovecot.
Why do you send that request to me personally in Cc:?
I have the dovecot version 2.0.9 installed on RHEL linux 6.10 version. It's a single/standalone Live server.
Now I have created another server with the same configuration for the resilince purpose. I also tested and I am able to send the emails to both of the dovecot servers separately/individually. They are working fine.
Now I have added those two servers under a F5 load balancer and created a FQDN (example: testing.test.com). I changed the rules to send the traffic to FQDN "testing.test.com", where it should redirect the email to one of those 2 servers.
When I sent the email to FQDN "testing.test.com", I am getting the below error.
pf1_inbd/smtp[30292]: 66A5F5F6: to=xxxxx@yyy.com, relay=testing.test.com[xxx.xxx.xxx.xxx]:25, delay=13, delays=0.09/0.08/13/0, dsn=4.4.2, status=deferred (lost connection with testing.test.com [xxx.xxx.xxx.xxx] while receiving the initial server greeting)
That's the MTA on port 25 not reacting as it should. That's no dovecot iisue.
Could you please let me know how to fix this issue? It's a great help for me.
Thanks & Regards, Kishore Potnuru
Alexander
Hi All,
I need your help on one of the issue in Dovecot.
I have the dovecot version 2.0.9 installed on RHEL linux 6.10 version. It's a single/standalone Live server.
Now I have created another server with the same configuration for the resilince purpose. I also tested and I am able to send the emails to both of the dovecot servers separately/individually. They are working fine.
Now I have added those two servers under a F5 load balancer and created a FQDN (example: testing.test.com). I changed the rules to send the traffic to FQDN "testing.test.com", where it should redirect the email to one of those 2 servers.
When I sent the email to FQDN "testing.test.com", I am getting the below error.
pf1_inbd/smtp[30292]: 66A5F5F6: to=xxxxx@yyy.com, relay=testing.test.com[xxx.xxx.xxx.xxx]:25, delay=13, delays=0.09/0.08/13/0, dsn=4.4.2, status=deferred (lost connection with testing.test.com [xxx.xxx.xxx.xxx] while receiving the initial server greeting)
Could you please let me know how to fix this issue? It's a great help for me.
Thanks & Regards, Kishore Potnuru
"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.
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.
Dovecot doesn't do the mailing between systems, so i assume you've got postfix configured? And do you have shared storage behind your two dovecot instances so that your users don't have to login to multiple systems to get emails?
Did you read the docs at:
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.
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.
Sounds like you haven't actually setup your system correctly. But we're not going to be able to help until you provide more details. It's also not clear from the about log file *which* server gave you this error.
It would be smarted to start from scratch with an upto date install of dovecot (and postfix in my opinion) according to the Dovecot docs above, and test that out in a test environment. Then you would use 'doveadm' sync to migrate user accounts over to the new system.
John
Hi John,
Thank you for the reply. Actually it was setup like this by another member, who left the team/company recently. Now it came to me to handle that responsibility. That's how I got in to this. At present I am not able to migrate/upgrade immediately. Because it sends emails around 100K+ emails everyday and I do not want to disturb that.
Coming back to your question, Actually the connection is :
O365/Outlook >> SMTP Gateway Server >> testing.test.com >> 2 POP3 servers.
Actually "testing.test.com", that is FQDN name set in F5 load balancer, where it is having the 2 POP3 servers to route the emails. When the email was sent from Outlook/O365, first it goes to SMTP Gateway Server. Now the SMTP Gateway server has the postfix rule to send it to " testing.test.com". In this location, I am getting the error in SMTP Gateway Server, where it is not able connect ( lost connection with testing.test.com [xxx.xxx.xxx.xxx] while receiving the initial server greeting).
In SMTP Gateway server, instead of "testing.test.com", if i give the name/ip of any POP3 server, then email delivery is happening successfully to that POP3 server. The above error is coming only when i use the fqdn " testing.test.com", instead of direct POP3 server.
Please let me know if you need any more details. Could you please help me here.
Thanks, Kishore Potnuru
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.
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.
Dovecot doesn't do the mailing between systems, so i assume you've got postfix configured? And do you have shared storage behind your two dovecot instances so that your users don't have to login to multiple systems to get emails?
Did you read the docs at:
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.
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.
Sounds like you haven't actually setup your system correctly. But we're not going to be able to help until you provide more details. It's also not clear from the about log file *which* server gave you this error.
It would be smarted to start from scratch with an upto date install of dovecot (and postfix in my opinion) according to the Dovecot docs above, and test that out in a test environment. Then you would use 'doveadm' sync to migrate user accounts over to the new system.
John
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
participants (4)
-
Aki Tuomi
-
Alexander Dalloz
-
John Stoffel
-
Kishore Potnuru