Error when sending Email (perl)

[#1]

When calling sendmail to send a single email, I sometimes get this error:
collect: Cannot write ./dfs28CWBSo015462 (bfcommit, uid=489984, gid=12): Read-only file system queueup: cannot create queue file ./qfs28CWBSo015462, euid=489984, fd=-1, fp=0x0: Read-only file system

[#2]

Hi, can you raise a support ticket concerning this one and provide me with as much detail as you can, including directions explaining how the problem can be replicated? I'll then do my best to work out/find out what's happening.
Thanks.