Let me expand...

I have a client who is unhappy with their current hosting situation. They want me to move their website and domain across to my hosting platform. I can do this.

However I have realised that the company has:

1) A number of existing IMAP accounts

I understand that I can use a tool like imapsync in order to transfer the mailboxes and hopefully incur only a small amount of downtime with the emails during this process. Can anyone offer any advice regarding the transfer of IMAP mailboxes from one server to another.?

2) An SMTP Relay

Another company supplies my client with an SMTP relay. I've only really just found out what this is. I understand that emails are sometimes undelivered to the client and a mail relay routes incoming mails through another (more reliable?) server in order to keep trying to resend emails so none are missed.

Is this neccessary in this day and age? Does my Plesk 10 Panel Linux Server come with any internal mail relay? Maybe I could use another service like mailjet or elasticemail instead?


Am in in for a lot of hassle moving email accounts or is this a
fairly transparent process?
What should I look out for and how
can I make this hosting transfer seamless (or nearly seamless)?
When I move the domain to my server (and the IP changes) this will interrupt the current mail relay. Will my client's emails continue to be delivered?



Question: What is the kernel doing when I bring a TUN/TAP interface up
Answer: OK, I can't get the packet imported into Wireshark (there must be some headers extra or missing, not bothering to figure that out) but, this is IPv6. From your first frame, you see ff 02 00 00 00 00 00 00 00 00 00 00 00 00 00 16. That's the IPv6 address ff02::16, used for MLDv2. 

Edit: from your first frame, here is the IPv6 part in a format Wireshark can understand when you select "File->Import" and pick Encapsulation type of Raw IP or Raw IPv6 (this starts after 36 octets of other headers):

0000   60 00 00 00 00 24 00 01 00 00 00 00 00 00 00 00
0010   00 00 00 00 00 00 00 00 ff 02 00 00 00 00 00 00
0020   00 00 00 00 00 00 00 16 3a 00 05 02 00 00 01 00
0030   8f 00 d1 ff 00 00 00 01 04 00 00 00 ff 02 00 00
0040   00 00 00 00 00 00 00 01 ff ea 9c a0 00 00 


Edit(2): If you trim off the leading 4 octets 00 00 86 dd, then it decodes properly as an Ethernet frame.

Edit(3): Here is your whole capture, with those 4 octets removed from each packet and massaged so Wireshark can import it (encapsulation Ethernet): http://pastebin.com/sUfCfPC4