Zimbra Server very slow - Too many SMTP connections

[pc-nico]

yes the server has one nic with a private IP, which is translate by the firewall to
a public IP Adresse....

[uxbod]

you could look at putting in a second card for local site traffic, especially if you primary NIC is getting loaded by external traffic. Or look at using bandwidth throttling using TC.

[pc-nico]

i think, i have found the problem, but not the answer....

i only have the Problem, that the server don´t accept SMTP connecten from
WEB-Mailer or Thunderbird...

after i disconnect the Internet-Access i get acces to smtp to send a mail
using thunderbird...

The Problem are to many smtp-connects from outside, so not enough for inside
available...

You Wrote

You should look at throttling the connections either by using Postfix

can you give me an advice how?

[uxbod]

You could add a SMTP port only for internal clients :- Adding additional SMTP listener ports - Zimbra :: Wiki

[pc-nico]

good idee.... but the webmailer use the default smtp port.....

is they no way to block the many requests?

[uxbod]

Postfix Connection Tuning

NOTE: I have removed your other post as we are attempting to resolve within this one. Please do not start a new thread for the same thing.

[pc-nico]

sorry for double posting... but i think you the only one how read this topic, because
the subject don´t describe the problem....

thx

[pc-nico]

the options
smtpd_hard_error_limit = 3
smtpd_soft_error_limit = 2


are already set :-(

[uxbod]

Other options are available :- SMTPD_CLIENT_CONNECTION_RATE_LIMIT

[pc-nico]

smtpd_client_connection_rate_limit = 120

takes no effect :-(