To encourage more people to migrate to Zimbra, we need to have better migration tools to make it easy and frustration-less for them to do so.

One of the most frustrating migration headache is importing emails and switching of email server thru the change of MX record.

During such migration, there will be a TTL timing whereby some emails to still get to the old email server while some will get to the new Zimbra server. It's troublesome to ensure that both sides will get downloaded to client's email app as we need to switch to IP address to target the correct email server. And when this happen, all emails will get downloaded, creating frustrating duplicates.

While Allow only mail from now to be downloaded feature is really nice, it will
mean that between the last check email to now, those emails will not have a
chance to get downloaded.

Thus, it will be more useful if there is an option to select Allow only mail
from last week to be downloaded or even better, allow us to select how many
days.

Please vote for this enhancement at: https://bugzilla.zimbra.com/show_bug.cgi?id=53783