Missing emails/ permanent send receive error & security warning

Question

Following a "successful" migration from Plusnet to Greenby, all my saved emails in folders from 2021, 2022, 2023, 2024, 2024 & some folders from 2026 are missing along with all messages in my Inbox before around 16:00 hours on Friday 13th March. At the bottom of my email window there is a permanent 'send/receiver error' which no amount of clicking on 'send & receive all folders' resolves. In addition whenever I send an email I get themessage:

If this is behind other open windows I often don't realise messages are still stuck in my outbox until I log off at the end of the day. How can I resolve this & retrieve my missing emails please? This is the second time since migration this has happened. Greenby are being spectacularly unhelpful. I'd really like someone to talk me through it was I'm frightened to try any fix myself as losing my emails is proving both traumatic & time consuming.

Answer 1

The symptoms indicate two separate issues: classic Outlook cannot connect correctly to the mail server after the migration, and historical mail is not currently available in the mailbox/profile Outlook is using.

Use these steps, in order, to restore send/receive and then investigate missing mail.

1. Check Outlook.com / webmail directly
   Since the tags indicate Outlook.com / Outlook on the web, first sign in to the mailbox in a browser. If the older messages and folders appear there, the data is safe and the issue is only with the Outlook client profile or sync. If they are also missing in webmail, the data is not in the current mailbox and must be recovered by the provider (Plusnet/Greenby) from server backups or archives.
2. Confirm the account is not blocked and storage is not full
   In Outlook.com, if cloud storage is full, sending and receiving stops and messages to the account are bounced and unrecoverable. Check mailbox storage using the storage link in the Outlook.com article and free space if needed. Also verify the account is not temporarily blocked and, if necessary, follow the steps to unblock it.
3. Fix the permanent send/receive error in classic Outlook
   Because send/receive is failing and messages stay in the Outbox, follow the Outlook send/receive troubleshooting steps:
   • If the account password was changed during migration, update the password in Outlook so it matches the provider’s settings. The article notes that changing the password on the website requires updating it in classic Outlook as well.
   • Check whether any message in the Outbox has large attachments (typically over 20 MB). Open the Outbox, start with the oldest stuck message, remove large attachments, or replace them with links, then send again.
   • If send/receive still fails, repair the Outlook profile and, if necessary, create a new one. The profile controls how Outlook connects to the mailbox and a damaged profile can cause persistent send/receive errors. Use the steps in “Fix your Outlook email connection by repairing your profile” and “Create an Outlook profile.”
   • If Outlook add-ins are involved, start Outlook in safe mode (outlook.exe /safe) and test send/receive. If it works in safe mode, keep the new profile and disable problematic add-ins.
   • If Outlook reports data file errors, run the Inbox Repair Tool (scanpst.exe) against the Outlook data file (.pst) as described in “Run the Inbox Repair Tool.”
4. Address the security warning dialog
   The “Internet Security Warning – The target principal name is incorrect” dialog appears when the server name configured in Outlook does not match the certificate presented by the server. This is a configuration issue on the account settings (server name/port/SSL) and must be corrected using the settings provided by Greenby. Until the correct server name and ports are entered, Outlook will continue to show this warning and may not sync reliably.
5. Check for rules or hidden moves of mail
   If only certain folders or one address is affected, verify that no rule is diverting mail to unexpected locations (for example, RSS Feeds or another folder). A misconfigured rule can make it appear that messages are missing when they are being moved automatically.
6. If messages are still missing
   • If the messages are not in Outlook.com/webmail and not in any local PST/OST file, they are not present in the current mailbox. In that case, only the provider (Plusnet/Greenby) can restore them from server backups or confirm whether they were deleted or not migrated.
   • If the messages are visible in webmail but not in Outlook, completing the profile repair or recreating the profile should trigger a full resync and bring the folders and historical mail back into Outlook.

If none of these steps restore the missing mail and send/receive remains in error after profile repair and correct server settings, contact Outlook.com support from within Outlook.com (Help → Still need help?) so support can review the mailbox state and migration impact.

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References:

• I can't send or receive messages in Outlook
• Can't send or receive email in Outlook.com
• Email is missing from your Outlook.com inbox