Welcome, if you would like to post a comment please register.
We also encourage you to explore all things Zimbra with our team and members of the community.
Our zimbra has encountered problem with big attachments. When the sender from outside (e.x. gmail.com, yahoo.com and etc.) is sending a mail which is too big than limit is set on our zimbra server (10MB) message is lost.
Sender doesnt receive any notification that mail is too big.
On server there is no log about message which is too big.
What version of Zimbra are you using? We are using 6.0 Foss and we've tried reproducing your error. Everytime we send a file from Gmail that is to big we always recieve a bounce alert back to our Gmail address. Do you have NDR disabled? Have you tried sending an attachement yourself from Gmail to verify if a bounceback message comes back?
Yes i have tried by myself to send from outside to our server.
I haven't touched any NDR parameters. How to check if it is enabled on server ? As I understand it should be on by default.
Bugzilla
Wiki
Source
No response on too big attachments 
Linear Mode
