Dovecot pop3 feature

[Markus Eckerl]

Hi all,

we are using dovecot since several years without any problems or trouble.

Now we are having trouble with a few of our customers - they are trying 
to fetch their emails every few seconds (3-5!). These customers are 
using Microsoft Exchange Server and also all of these customers are 
cared by the same IT Professional...

Is it possible to send a pop3 "LOGIN-DELAY" if the customers last login 
is only a few seconds away? A simple firewall rule for rate limiting is 
not possible because most of them are business customers and they are 
connected using NAT.

In RFC2449 
<https://www.iana.org/assignments/pop3-extension-mechanism/pop3-extension-mechanism.xhtml> 
I read that the pop3 capability "LOGIN-DELAY" exists. But it seems that 
dovecot does not offer this? Why?

Kind regards

Markus