Camera Alert Email not showing Pictures

[GrantThorntonAus]

Using external storage (NFS) and pictures dont come through on the alert emails. instead i get the following error at the bottom of the email:

"Notice: Due to excessive system load, one or more requested graphs, pictures, or audio clips were not able to be delivered"

If i turn off external storage they come through. Im not convinced its network latency as the emails worked fine when i was using SMB on the same server for external storage. I had to switch to NFS after we disabled SMB1.

Anyone else had this issue and found root cause, and hopefully a workaround (other than turning off external storage)