Please clarify. Are you stating that messages sent from two other PCs and an Iphone do not appear in your sent folder? That could happen if one or more of the devices store sent messages locally. If the other devices all show sent messages done by the others, but none show sent messages from your PC, then your PC is storing messages locally or not at all. Check the copies&folders section of the account. I also suggest sending a test message from one of the other devices and verify which devices see the sent message.

Hello David, Thanks for helping out. All PCs archive copies of the IMAP messages locally. In the Copies and Folder section, I have selected the first option on all PCs.

When sending messages, automatically: Place a copy in: "Sent" Folder on:

Testing mails: Messages sent from the Iphone are not synchronised on either PC platforms. A test mail from my laptop now synchronizes with the main PC (but that is not often the case. Could it be the network???). Unfortunately, I can't test the third PC now because it is in a different place.

If the laptop and PC are showing the message, then thunderbird is doing its thing. Network may be slow, but should eventually show the message. The phone appears to be using POP and should be checked. If true, you need to remove the POP account, and then create again in IMAP. That is, you cannot change POP to IMAP.

Thanks for answering so quickly! I'll check the PC's later, hopefully there is only a slow network. But the iphone account is in IMAP.

Then check that other PCs are seeing messages sent from the phone. It's possible to use IMAP for incoming and storing locally when sending. Since you're encountering inconsistencies, each device needs to be checked for receiving and sending.

Both laptop and main PC appear to not synchronize with Sent mails from the IPhone. I also tried to repair the Sent folder on both available PCs, but no sent mail from my phone appears after that.

If the PCs show sent messages sent from each other, then thunderbird and IMAP are working properly. if messages sent from the phone are not appearing, the problem is with the phone. You should also log online to see what is there. Send message from each device, including the phone. There should be three messages in sent folder online, one from each. Then, check the two pcs and the phone and see if each one shows three messages.

The messages sent from the phone are not synchronized in either PCs. The problem might be Zimbra, tho. Sent mail from the phone is shown in the mail Sent folder, while the sent mail from the PCs are only visible in the server folder of Zimbra-login.net. Hope you might have an idea what's going on there, otherwise I should contact my Zimbra provider...

if the phone's sent mail is not shown in the online account, I suspect the phone's setting is the problem. I would check there before contacting email provider.

Thank you David!