Insufficient disk space; try again later when trying to send mail

Question

I am trying to send an email with attachment using PHP and I get this error:

Insufficient disk space; try again later
Insufficient disk space; try again later
returntosender: cannot select queue for root
Insufficient disk space; try again later
returntosender: cannot select queue for postmaster
queueup: cannot create queue file qfp5M7HeoG001376, euid=51, fd=-1, fp=0x0: No space left on device

I checked and it seems that there is space:

Size  Used Avail Use% Mounted on
112G   89G   18G  84% /
 99M   22M   73M  23% /boot
4.9G   33M  4.6G   1% /tmp
4.9G  4.6G     0 100% /var

The file I'm trying to attach has less than 4MB. Any idea where this comes from and how can I fix it?

Answer 1

Obviously there is not space in /var which is where it will try & create the spool