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F5 and rate limits

Greg.Howley
Level 1
Level 1

We recently moved all user mail to a cloud service and wound down our internal mail servers.

Some internal applications still need to send mail (to both our internal users in the cloud and third parties) as well as some legacy apps that need to receive mail, so we kept our ESAs in place, at a much reduced load.

We have an F5 that causes outbound mail to all have the same IP address (network team tells me it can't be put in transparent mode, I don't really understand the reasons why)

A specific sender keeps getting mail delays when they try to send out their mass-mailings.

How can I identify this particular sender and apply a different policy to them to prevent there mail from getting delayed with "Too Many Connections"?

 

10 Replies 10

dmccabej
Cisco Employee
Cisco Employee

Hello,

 

The first thing you'll want to do is identify the Sender Group and correlating Mail Flow Policy that the user is hitting, which can be found by searching through the Message Tracking and/or mail_logs. Once you find the Sender Group / MFP, you can then either increase the throttling universally, or you can setup a bypass for this particular Envelope Sender.

 

These settings can be found in the GUI under Mail Policies --> Hat Overview --> Select MFP --> Expand Rate Limit for Evenlope Senders --> Increase the limit or setup an Address List Exception for that sender. 

 

Thanks!

-Dennis M.

Libin Varghese
Cisco Employee
Cisco Employee

What does the message tracking for these emails show?

 

If you see the "Too Many Connections" after an ICID is created it would display the sendergroup and mail flow policy matched which can be verified under Mail Policies -> Mail Flow Policies -> Accept/Relay etc.

 

Regards,

Libin Varghese

But is there any way I can prioritize mail for this sender only?

Because the f5 presents everything with the same IP, all outbound mail gets the same sender policy.

 

ESA treats all emails with the same priority and passes them through the workqueue processing one by one.

 

Regards,

Libin Varghese

So I have to up the connection limits for all internal senders because I
can't differentiate by IP or sending host to apply separate policies.

Thanks

Hello,

 

If you're referring to a specific user (Envelope Sender), then I provided the resolution in my first reply. You'll need to setup an Address List for this Sender and enable an Exception. If you're referring to an actual host server (IP address), then no, there would be no way to prioritize that traffic since we see everything coming from the same single F5 IP.

 

Thanks!

-Dennis M.

sorry - I was tired last night and only the "universally" part registered.

 

I will try the Envelope Sender exception

 

Thanks again.

 

Not to worry :) Hopefully that helps!

 

-Dennis M.

Grep the mail logs (see Libin''s post) if you.can't find it in the mail.logs, check the F5 toale sure it isn't throttling the connections...

Revisiting this.

 

The issue is at the connection level, so how will it even get to the point where is assesses the Envelope Sender?