Change MX record   

Hello,

We are planning to have our Exchange start to receive email next month
(Oct).

Our current outlook setting for each users :
- Pop3 account to send and receive email from our email provider
- Exchange account to host the email in our internal exchange server.

Now, our MX record are pointing to the email provider, so, all our
emails go there and we use the POP3 account in outlook to receive
email but store in the our exchange mailbox.

If we want to receive email by our exchange directly, we need to
change the MX record to point to our static IP. (and forward port 25
to our internal exchange server).

I was told that it may take 3 days for all the other internet DNSs to
have the MX record changed. That means, once we change the mx record,
within the next 3 days, if emails send to our domain, there may be
possibility that the email still going to our email provider or going
to our exchange server, depends on the DNS mx record that the sender
used. However, since we still have pop3 setting in our outlook, we
should be able to receive the email that receive by our email provider
through the Pop3 account in outlook. That means, we should be OK and
shouldn't lost any email. In the client side, they shouldn't notice
any changes and they just keep receiving email from POP3 and accessing
their Exchange account. 3 days later, after all internet DNSs have our
mx record changed, all email that send to us should come in through
Exchange.

We will disable the email provider's services 2 months later.

Will this work or I miss something ?

Please advise !

Thanks,
Eddie

date: Thu, 27 Sep 2007 10:21:47 -0700   author:   unknown

Re: Change MX record   

eddiehmwong@hotmail.com wrote:
> Hello,
>
> We are planning to have our Exchange start to receive email next month
> (Oct).
>
> Our current outlook setting for each users :
> - Pop3 account to send and receive email from our email provider
> - Exchange account to host the email in our internal exchange server.
>
> Now, our MX record are pointing to the email provider, so, all our
> emails go there and we use the POP3 account in outlook to receive
> email but store in the our exchange mailbox.
>
> If we want to receive email by our exchange directly, we need to
> change the MX record to point to our static IP. (and forward port 25
> to our internal exchange server).
>
> I was told that it may take 3 days for all the other internet DNSs to
> have the MX record changed.

Not if you can get whomever hosts the DNS to change the TTL (time to live) 
to something nice and low, starting this several days beforehand. Then the 
rest of the world will get the new/updated info very quickly once you flip 
the MX record....and you can later change the TTL back to its defaults.

>  That means, once we change the mx record,
> within the next 3 days, if emails send to our domain, there may be
> possibility that the email still going to our email provider or going
> to our exchange server, depends on the DNS mx record that the sender
> used. However, since we still have pop3 setting in our outlook, we
> should be able to receive the email that receive by our email provider
> through the Pop3 account in outlook.

Yep - that should work.

> That means, we should be OK and
> shouldn't lost any email. In the client side, they shouldn't notice
> any changes and they just keep receiving email from POP3 and accessing
> their Exchange account. 3 days later, after all internet DNSs have our
> mx record changed, all email that send to us should come in through
> Exchange.

Yep.
>
> We will disable the email provider's services 2 months later.

Well, before then, remove the POP accounts from Outlook....they'll annoy 
your users.
>
> Will this work or I miss something ?
>
> Please advise !
>
> Thanks,
> Eddie

date: Thu, 27 Sep 2007 20:12:16 -0400   author:   Lanwench [MVP - Exchange]