We are hosting email with a hosted exchange provider so it is separate from the website.
The domain is registered with 123 reg and the nameservers are pointing to a server where the web files and database sit. From our control panel we have configured the appropriate MX/DNS entries to point the email to the hosted exchange server.
If our server went down where our website sits, will our email go down too because the MX records and DNS entries are hosted on this server?
Thanks
It depends. DNS is usually cached, so any email server that recently sent you a message and the TTL hasn't expired, should be able to reach you. Any new requests could go unanswered.
That being said, what I described will not provide any reliable redundancy. The best solution is to have another authoritative dns server in a separate location in case your server goes down.
It sounds like you're worried about missing messages. If your downtime isn't more than 24 hours you should be ok. Most email servers will try several times to send a message before it's returned.