Most companies limit the maximum size of outgoing mails to the internet.
In case of an existing size limit for outgoing mails, Lotus Notes will send Non Delivery Reports back to the users containing the original attachments. This is a good behaviour, because users can easily use the “resend” functionality to change the mail and send it again to the intended recipients.
But especially when users are working with local mail files, this can cause a lot of additional traffic sending all mails and Non Delivery Reports with attachments.
In this case, it would be a better way to just send the mail out to the recipient. The Non Delivery Report is causing only additional traffic and consuming additional disk space and performance on the Domino servers and Notes Clients.
Users with low-bandwidth connections are mostly lucky to finally get a mail with attachments sent to the server for delivery, but after a few minutes, they sadly recognize that the Notes Client is starting to replicate the Non Delivery Report down to the machine including again the whole attachments.
The best solution would be to block mails exceeding the size limit before users can send them. This is, for whatever reason, not possible in Lotus Notes (at least not without additional tools or mail template customization).
Solution / Workaround
To avoid at least the traffic back to the clients, you can implement a smart workaround without changing too much to the standard mail routing procedures.
You can just define the mail size limit as before and let the Domino server create the Non Delivery Report. Now you can specify a server rule, which grabs this Non Deliver Report (and only these reports) and put it to a custom database you have created.
In this database, a scheduled agent runs to remove the attachments from the mails before they get delivered to the original intended recipients.
This avoids a lot of traffic, disk and performance usage without changing too much to the standard routing procedure.
We just have another hop in between to remove the attachment, but we don’t have to create custom reports or mails or something like that. And we don’t interrupt the standard mail routing; we only interrupt the routing of the internal Non Delivery Reports.
How to configure
You can implement this solution in a few minutes.
Download the mentioned custom mailbox or just create your own.
- Configure the message size limit (if not already done) in the configuration document of the last Domino server (or multiple servers) before the mails leave your domain:
- Put the custom mailbox to your server and change the ACL to allow manager access only for the current server and administrators. Users don’t need access.
Sign the database with your id or an appropriate signer id.
- Activate the two agents in the newly created database.
Agent “sendNDR”: Creates a copy of each incoming mail without attachments and delivers it to the original intended recipient. Schedule this agent to run every 5 minutes.
Agent “purge (30 days)”: Deletes all mails already processed after 30 days.
- Create a server rule to move all Non Delivery Reports larger than your specified message size limit to the newly created database.
You can use multiple conditions to ensure that only the mails are getting “grabbed” you want to.
Additionally, you can define more or other conditions.
All mails have to be moved to the created database:
- Restart your router task to activate the configuration
Now you can test your implementation. Just send a mail larger than the defined maximum size.
A standard Non Delivery Report will be sent to the user without attachments.
By the way…
Even if you limit the maximum message size in the router restrictions tab of the configuration document for example to 10 MB, users can still send a mail with 9.5 MB to 10.000 Users!
See my corresponding blog post for details: Limit the total size of a sent mail including the number of recipients