How to reply to an ics invitiation without using googlemail I'm using the htc mail widget/app with an email account other than googlemail.com.
When an .ics invitation is attached to an email I can import the event into the phone's calendar but apparently I cannot confirm or reject the appointment.
Is there e.g. an app that you can recommend to send such repsonses - and maybe even display the list of participants (minor issue)?
It looks like this is a known issue. I'm using K9 mail and, while I would swear I've replied to meeting invites in the past,but I just tried sending my non-gmail IMAP self an invite from my google calendar and I get an ICS attachment and K9 Mail complains that it is "Unable to find a viewer for application/ics"

It looks like there are a couple of apps in the market that will handle this, though. Take a look at iscer and ICS Bot -- I haven't tried either but both profess do to do what you need.