An "unsafe attachment" is one that may contain a viral payload. It does
not mean that it is definitely infected, but some filters will
automatically flag such things even though the culprit may be perfectly
harmless. Usual suspects are any executable file type (.exe, .com, .pif
and so on) or Word documents (.doc - these may contain macro viruses), but
there are others.
The general rule of thumb is; if you don't know what it is, don't touch it.
For more information, try asking on one of the groups specialising in
Microsoft operating systems (this one handles RISC OS, hence "acorn" on
the end), or have a read through the UFAQ (www.ufaq.fsnet.co.uk)
--
//\ // Chika <zvl...@penfuarg.bet.hx. - ROT13>
// \// Hitting Googlespammers with hyper-hammers!
... If speed scares you, try Micro$oft Windows.