I need to move a client's website off their old host and onto their new host without changing their email server. I've read this extremely thorough answer on a similar question (https://serverfault.com/a/370295/112673) and I think I've wrapped my head around what to do, but I wanted to confirm I understand it correctly.
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EDIT - I have since realized my original strategy was dumb. This is now revised.
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These are the settings on the zone file for the current host:
localhost.website.com Address Record (A) 127.0.0.1
website.com Address Record (A) 1.2.3.4 (current web server IP)
website.com Mail Exchange Record (MX) preference=10, host=website.com.
ftp.website.com Canonical Name (CNAME) website.com.
imap.website.com Canonical Name (CNAME) website.com.
news.website.com Canonical Name (CNAME) website.com.
pop.website.com Canonical Name (CNAME) website.com.
smtp.website.com Canonical Name (CNAME) website.com.
www.website.com Canonical Name (CNAME) website.com.
I am planning to change these settings to
localhost.website.com Address Record (A) 127.0.0.1
website.com Address Record (A) 5.6.7.8 (new server IP)
website.com Mail Exchange Record (MX) mail.website.com.
www.website.com Canonical Name (CNAME) website.com.
ftp.website.com Canonical Name (CNAME) website.com.
news.website.com Canonical Name (CNAME) website.com.
mail.website.com Address Record (A) 1.2.4.5 (old server IP)
imap.website.com Canonical Name (CNAME) mail.website.com.
pop.website.com Canonical Name (CNAME) mail.website.com.
smtp.website.com Canonical Name (CNAME) mail.website.com.
If I understand correctly, this will point the actual website website.com to the new server IP, but ALL email related things to mail.website.com which is still pointing to the old server IP.
Additionally, is there any way for me to test this setup before going live? The answer I referred to earlier mentions you can do this yourself with my hosts file locally but I'm not sure exactly how to go about setting that up.