Outlook non-delivery to 'graylisted' addresses

[yourdisplayname]

Copy addresses to a message have failed to be delivered with a response
' 5.4.7 - Delivery expired (message too old) [Tiscali] 421-'Your address
has been graylisted. Try again later.'

I understand that blacklisted addresses are those of possible spammers that
are put into such a list. (The recipients certainly don't fall into this
category).

Has anyone any idea how to overcome this please?

 

[Brian Tillman]

(e-mail address removed)

Copy addresses to a message have failed to be delivered with a
response ' 5.4.7 - Delivery expired (message too old) [Tiscali]
421-'Your address has been graylisted. Try again later.'

This usually means that the sender's address, not the receipient's address,
has been graylisted.

I understand that blacklisted addresses are those of possible
spammers that are put into such a list. (The recipients certainly
don't fall into this category).

Graylisting is a temporary categorization of the incoming mail. The
receiving prohibition is usually removed in a reasonably short time, after
which the receiving server will accept the message, usually within the retry
limits of the sending server.