Calendar invites do not allow resend of accept/deny when initial attempt fails.

[paradisaeidae]

Often the config is the issue.
Being that the first 'known' account with email received addy is used to attempt smtp.
There are a number of reasons the smtp attempt may fail.
Though the invitation is not aware of this being so.
No way of re-setting invite to 'unread'.
That I could find.
Firefox, Mozilla, Thunderbird is/are amazing.
Thanks!
MarkT