How to Limit user to Sending Emails with Attachments

[scarletts]

I am having a server and hosted multiple domains and my clients want to have some restrictions sending emails , I am looking for a solutions for following

1. Need to Restrict Sending emails with Attachments
2. Need to Restrict Sending Emails to Public Domains (like yahoo, gmail, live.com, hotmail)

1. Need to Restrict Sending emails with Attachments
my vps server has multiple domains , each domain users has many email users , they want restrict their user to send emails with attachments to their receipients.*****

Eg: some user not allowed to send emails with attachments , if any user's send emails with attachemnts automatically deleted by the server and only mails contents should reach to their recipient.*****
some of the user are allowed to send emails with attachments,*****
also if any one send emails with attachment that particular domain administrator should get the email notifications with who sents emails with attachments , subject of the email id, Attached file name .

2. Need to Restrict Sending Emails to Public Domains (like yahoo, gmail, live.com, hotmail)

another request my clients wants to restrict their mail user (some mail users) to send mails to public domains like yahoo, gmail, live.com, hotmail mail id's , some users are allowed to send emails to public domains as mentioned above.
any shell script or Piping program to control this request, please advice

[praveenk]

Simply purchase cPanel control panel and define filter rules, for more information refer to the following URL and configure the filters as per your requirement

http://www.exim.org/exim-html-current/doc/html/spec_html/filter_ch-exim_filter_files.html

[scarletts]

Thanks for your advice!

[AdrianG001]

Most email systems limit the size of attachments for two reasons.


Controlling the size of the mail store. If there was no limit on the size of attachments, then users would send huge files causing massive storage issues for the back-end mail store.
Performance. Email systems aren't optimized for transferring large files. Client systems often download messages to the local computer. This means that messages (along with attachments) are downloaded even if the user doesn't need (or want) the attachment at the time. Dedicated file sharing systems (e.g. DropBox) solve this by keeping the file on the server until the user specifically requests to download it. Some email clients can be configured to behave this way. Dedicated file sharing systems use more efficient protocols to download files.