Zitat von jayesh shinde <jayesh.shi...@netcore.co.in>:
Hi , I am facing problem of bandwidth choke issue between remote location and SMPT server. Please giude for below. Want to know how the other busy servers are handling such issues. scenario :-- ------------- 1) I have centralize high traffic SMTP server with postfix-2.10.0-1.el6.x86_64 and different locations offices. 2) Branch users send the emails from different email clients like MS outlook or Thunderbird etc ... 3) Currently we have set global 5 MB message size restriction in postfix's main.cf . If any one send email more than above 5 MB that get reject and end user get notification pop-up in email client. Problem :-- -------------- 1) Some time few end users are sending more than 5 MB emails , which getting travel from Location office to Server and utilizing higher bandwidth. 2) Server reject the emails when complete email get transfer i.e from email client to server. But not before the actual mail transfer. 3) When many different location users send such higher size email traffic , the internet bandwidth is either getting chock or utilizing very high. 4) Some time such higher size emails get stuck in outbox of email clients , and after certain auto set "send/receive" interval the email client sending that email again to server. Expecting solution :-- --------------------------- 1) If any one send email more than 5 MB , then server must detect the mail size before the actual mail transfer from desktop or server . And base on that server must either accept or reject the email with define rule set. The rule set could be either for email id or domain or IP. 2) I came to know that every email client don't send the "email size" information in first mode of SMTP transaction ( I am not sure about this. ) But if this is the case , then which are the standard email client which send the "email size" information in first SMTP transaction mode ? So that with some customized milter or 3rd party script the size base restriction policy can apply and issue can control
The server has no way of detecting the size of a mail it has not yet received. The server announces the size it is willing to accept and the client have to detect that it won't fit. That's the way SMTP works. Unfortunately there are Clients around (Outlook!!) which doesn't check for size and don't respect a "no" (permanent failure) as a "no" and simply retransmit the same message over and over again.
Is there any method / parameter in postfix config by which I can control this situation ?
No, you can only scan the log and block offending/stupid clients by firewall or access list from using SMTP to your server at all.
Regards Andreas
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