Auto serial number for every incoming message

[Waseem Qureshi]

How can I apply a unique serial number in ascending order (in subject field or beginning/end of message) for every incoming message that hits my domain? Kind of auto-support ticket system so that every message is given a unique id and for internal ref. with can talk more on unique ID instead of who, when what the message was spending time searching the messages... search just by ID that's it...

[#2]

Not in Exchange Online. And why do you think users will remember the ID to search by rather than the senders name or other keywords?

[#3]

If not in exchange online then how can I do it?

My email volume is more than 1000 emails a day, and we keep referring to past emails frequently. So if I’ve an email with ID say 7,899, I’ll pass this to my colleague instead of forwarding again or asking him search for X email on X date etc