A few users have reported that attachments will fail with webmail. When I tried it myself, I discovered that any attachment greater than 1 MB will fail with:
DB Error: unknown error
It takes a filesize of ~950 KB or less before it will succeed, which leads me to think Horde temporarily stores attachments in a database, and is therefore constrained by the MySQL packet size. Can the filesystem be used instead? It is misleading to have Horde say the max attachment size is 128 MB (upload/post/memory limit), while in fact it is less than 1 MB.
The fix we’ve used in the past was to edit /home/interworx/etc/my.cnf and inrease the max_allowed_packet value to something much higher, e.g.:
max_allowed_packet = 10M
And then restart InterWorx. As for making Horde use the filesystem instead of the database, I don’t remember off the top of my head if you can. I’d check the Horde docs for the authoritative answer.
I could not find a better solution (filesystem), so I increased the MySQL max packet size. I set it to 16 MB, which should cover most cases, but unfortunately Horde still says the max attachment size is 128 MB. I am sure it is just asking PHP for the max upload size, but that needs to stay high in case a customer with a moderately large size wants to restore their own backup by uploading it through SiteWorx.
Thanks for your help on this. If it is a bug, please add it to the list as “very low priority.”
One question: Does anyone know why the max packet size defaults to 1 MB? Is it is potential problem to set it higher?