Prevent Plesk overwriting Configuration Files or set custom configuration

[nocrash]

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PRODUCT, VERSION, MICROUPDATE, OPERATING SYSTEM, ARCHITECTURE

11.0.9 Debian 6.0 110120608.16, patch version="41", x86_64 GNU/Linux

PROBLEM DESCRIPTION

There are some modifications made at main.cf concerning the
* "mailbox_size_limit"-Bug
* useing the official SSL cert from Plesk instead of the custom generated one
* SMTP Auth Users may not be blocked by the RBLs

/etc/postfix # diff main.cf main.cf.bak
22c22
< smtpd_tls_cert_file = /etc/postfix/postfix_default.pem
---
> smtpd_tls_cert_file = /usr/local/psa/admin/conf/httpsd.pem
39c39
< mailbox_size_limit = 51200000
---
> mailbox_size_limit = 0
54c54
< smtpd_client_restrictions = permit_mynetworks, reject_rbl_client ix.dnsbl.manitu.net, reject_rbl_client cbl.abuseat.org
---
> smtpd_client_restrictions = permit_mynetworks

How to keep Plesk from overwriting this configuration or other ones for example proftpd ?


STEPS TO REPRODUCE

every plesk hotfix that want the file to be modified


EXPECTED RESULT

at least custom modifications should not be overwritten

ANY ADDITIONAL INFORMATION

the "mailbox_size_limit"-Bug is known since a long time

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