I recently switched my incoming mail server, on the advice of my ISP. How come, when I switch back to the old, all of the same messages come through again? If I don't "clean out" these messages on the old server, does it make a difference?

Ace said:

nah, that's a problem for your ISP. If you think there's something confidential there you might want to delete that, but if it's all penis enlarger stuff you can just leave it at that.

BlueZebra said:

But the old server is from a different ISP.

wait ... you mean when you retrieve mail from server 2, you get your mail. When you switch to server 1, you receive the same mail.

You don't have to do anything. They have multiple mail servers for redundancy (probably in different datacenters too. Might be they are phasing out server 1, still they'll have multiple (in some type of cluster/ high availability setup).
Synchronisation between databases might be a little slow, not caught up before you retrieved your mail from server 1.

That said, don't worry about it.

that's damn near impossible. What's the domain ? The part after the @ in your e-mail address ??

BlueZebra said:

Yes.

Server 1 is from Bell and Server 2 is from the company that hosts our website.

Ace said:

orgnote me your domain, I'll check it out for ya.

BlueZebra said:

Can you draw a diagram?

... A simple one

A diagram would work but I still have to receive my copy of "The back of the napkin" and "slide:ology" is only due for september

it can be different things but it would be odd to receive the same mail on two different servers (especially if they're hosted by two different companies).

Why? The internet functions through DNS. DNS links your domain name (e.g. prince.org) to an ip address (e.g. 10.10.10.10). When you type in the domain, it's resolved to an ip address, your computer contacts the server on that ip address and retrieves the page you asked for (or the trojan you didn't ask for but was included on the porn page you asked for). E-mail works a little differently. When you send an e-mail, you send it to your outgoing mailserver. This server looks at the domain (the part behind the @) and requests the MX records for that domain. MX records represent the e-mail servers for that domain. There can be multiple MX records but they usually are prioritized. The server with the lowest priority (let's say 10) is the first server contacted, then the next, and so on until the mail is delivered succesfully.

that fact makes Ace's problem a little strange. It might be that some servers still have a cache of the old DNS (MX) settings but still the mail would be delivered to one server or the other, not both. Unless I'm missing something

sorry ...

BlueZebra said:

So... It's a bit like moving house but the post still gets delivered even though it has the old address on it

In the postal system you can have mail forwarded... can this happen with email without the recipient knowing? Geez.. I've confused myself

BlueZebra said:

Could it just be happening while the MX re-pointing propagates throughout the Internet? Still, though, each message would land in one place or another.

Are they old messages that have just been exported in a data file to the new mailbox?

FunkMistress said:

I thought about DNS caching but thought that would be a bridge too far for this forum and like you said, every message would land on one server.

I've moved countless mailservers and POPs are rarely exported, but it may be a possibility.

BlueZebra said:

Isn't it business email though? Wouldn't the business want their data exported, whether they were using POP mail or not?

FunkMistress said:

You got a point there. It all depends on how it is done but seriously I'd have to ask a mod to move this topic to slashdot before we elaborate

BlueZebra said:

Steadwood said:

"Mail forwarding" is kind of what happens when you re-point your DNS. DNS tells the postman where to deliver the letter. But the letter shouldn't arrive at both houses, which is what seems to be happening to Ace, unless we're reading this wrong.

FunkMistress said:

I see....

...I think

FunkMistress said:

BORING

NOT !