Email issues that can arise after migration
For most users, migration is a seamless process and email sending and receiving continues exactly as before.
There are a small number of situations where users have seen problems after migration, usually these can be sorted quickly by adjusting/fixing the settings in your email program.
1) General errors sending or receiving
The most common cause of post-migration problems is where the server settings in the user's email program or device were not set according to our recommendations. In particular, this can happen where an incorrect form of the incoming or outgoing server name was used, or where an unsupported combination of port number and encryption/security settings were used. In such cases, usually all that is needed is to adjust the mail program settings as per the recommendations:
Email account settings for all email programs and devices
2) Apple Mail Issues (IMAP Path Prefix)
We've seen a small number of migrated Mac Mail users report odd issues when moving items between folders, deleting items or when Sent items are moved to the Sent folder. This appears to affect only Mac users (not iPad, iPhone users) and mainly accounts that were set up a long time ago that have undergone many MacOS updates.
The displayed error may reference the "IMAP Path Prefix", the mail program appears to be unable to determine the correct path prefix and attempts to change it in the account settings do not work. In such cases, the solution is to remove the affected account from Mac Mail, and add it back in again.
3) Duplicated Messages (POP3 Users)
Some POP3 users have seen messages stored on the server re-downloaded by their POP3 email client on first connection after migration. This is usually a once-off duplication, however if a large number of messages were being stored on the server this can be a nuisance for users and take a while to complete. This depends on the exact email client and version in use - mainly it happens for Outlook users, less so for mobile devices.
This can be mitigated *before migration* in a couple of ways:
a) If possible, consider switching to IMAP on all programs and devices you use to access the server (this also allows synchronization of Sent Items and other folders between devices). Whether this is appropriate depends on your plan (mailbox size), message volumes and the way you prefer to use your email.
b) Configure your POP3 Email client not to leave messages on the server (if it is the only device accessing the mailbox) or in other cases reduce the time that messages are allowed stay on the server - the default in modern Outlook versions is 15 days, but may be longer in older versions. Do not do this if you are using both IMAP and POP3 to access the same mailbox.
c) If you are using IMAP (including Webmail) as well as POP3 or if you prefer not to remove messages from the server, instead move messages out of the inbox into another folder on the server. This folder will then be visible via Webmail or your IMAP client but will not be (re) downloaded via POP3.
