Hello,

We have a small company and we're thinking of transitioning to an Exchnge
based messageing system, and do away with all the hosted POP3 accounts.

I'm the one pushing this idea forward, due to a number of reasons. A
question was raised about incoming emails, when/if our Exchange goes down.
I did not have an answer to this question.

So I wanted ask the Gurus out there, what happens to all the incoming emails
when the Exchange goes down? Do all of them get bounced? Do they get stored
in the source Exchange server until ours is back up again? What are the
chances of loss of emails in that scenario?

Your input is appreciated.

Re: Incoming Mail When Exchange Server Down by Dvord

Dvord
Thu Mar 06 18:23:19 CST 2008

The internet is pretty fickle. Things happen all the time which are
completely out of the hands of mail admins which break the connection to
mail servers the world over.

Because of this, most default configurations for mail allow for retries. So
if the sending mail server cannot reach the receiving one, they will simply
wait some amount of time and try again. My SMTP server at home was
configured to retry every 4 hours for 2 days. After the first 4 hours, it
sent a message saying mail could be delayed. After 2 days, it will then
bounce.

Users are a little spoiled because for the most part, mail is sent without
obstruction. They assume it's always instantaneous, when in fact it is not,
and there are times it can be delayed.

No worries, if your server goes down for a few hours, you won't lose any
mail.

"Tom Bombadil" <Genius_Poster@Yahoo.com> wrote in message
news:4BE58FBC-1855-4416-B5EE-6847C84C9A31@microsoft.com...
> Hello,
>
> We have a small company and we're thinking of transitioning to an Exchnge
> based messageing system, and do away with all the hosted POP3 accounts.
>
> I'm the one pushing this idea forward, due to a number of reasons. A
> question was raised about incoming emails, when/if our Exchange goes
> down. I did not have an answer to this question.
>
> So I wanted ask the Gurus out there, what happens to all the incoming
> emails when the Exchange goes down? Do all of them get bounced? Do they
> get stored in the source Exchange server until ours is back up again? What
> are the chances of loss of emails in that scenario?
>
> Your input is appreciated.



Re: Incoming Mail When Exchange Server Down by Mark

Mark
Thu Mar 06 18:33:28 CST 2008

On Thu, 6 Mar 2008 14:53:13 -0800, "Tom Bombadil"
<Genius_Poster@Yahoo.com> wrote:

>Hello,
>
>We have a small company and we're thinking of transitioning to an Exchnge
>based messageing system, and do away with all the hosted POP3 accounts.
>
>I'm the one pushing this idea forward, due to a number of reasons. A
>question was raised about incoming emails, when/if our Exchange goes down.
>I did not have an answer to this question.
>
>So I wanted ask the Gurus out there, what happens to all the incoming emails
>when the Exchange goes down? Do all of them get bounced? Do they get stored
>in the source Exchange server until ours is back up again? What are the
>chances of loss of emails in that scenario?
>
>Your input is appreciated.

They will get stored on either the sending server until such time as
either your server comes back up or until the sending system gets
bored and times them out. Don't ask how long that is because it's
1000% down to the sending admins. Between a day and a couple of days
is not abnormal. Six hours was seen at one customer site by me this
week. If you take the service from your ISP (if they don't offer it
you've got the wrong ISP) then their SMTP relay will be added as a
secondary MX record on your domain so that if your server goes down
(or Internet connection, or firewall blah blah) then the mail will be
delivered to them and stored there until such time as you pull it down
(different configuration story so don't worry about it) or it will
keep trying to send to your Exchange server ad infinitum.

Re: Incoming Mail When Exchange Server Down by Tom

Tom
Thu Mar 06 19:41:16 CST 2008

Thank you gentlemen for your replies.

Mark, what you mentioned about ISP relays might be very reassuring to folks
over here. I'd never heard of the concept before. Do you have any more
information/links/articles on that? Thanks again!


"Mark Arnold [MVP]" <mark@mvps.org> wrote in message
news:a431t31ch18o8ofh710qvtsovk0u549mtk@4ax.com...
> On Thu, 6 Mar 2008 14:53:13 -0800, "Tom Bombadil"
> <Genius_Poster@Yahoo.com> wrote:
>
>>Hello,
>>
>>We have a small company and we're thinking of transitioning to an Exchnge
>>based messageing system, and do away with all the hosted POP3 accounts.
>>
>>I'm the one pushing this idea forward, due to a number of reasons. A
>>question was raised about incoming emails, when/if our Exchange goes
>>down.
>>I did not have an answer to this question.
>>
>>So I wanted ask the Gurus out there, what happens to all the incoming
>>emails
>>when the Exchange goes down? Do all of them get bounced? Do they get
>>stored
>>in the source Exchange server until ours is back up again? What are the
>>chances of loss of emails in that scenario?
>>
>>Your input is appreciated.
>
> They will get stored on either the sending server until such time as
> either your server comes back up or until the sending system gets
> bored and times them out. Don't ask how long that is because it's
> 1000% down to the sending admins. Between a day and a couple of days
> is not abnormal. Six hours was seen at one customer site by me this
> week. If you take the service from your ISP (if they don't offer it
> you've got the wrong ISP) then their SMTP relay will be added as a
> secondary MX record on your domain so that if your server goes down
> (or Internet connection, or firewall blah blah) then the mail will be
> delivered to them and stored there until such time as you pull it down
> (different configuration story so don't worry about it) or it will
> keep trying to send to your Exchange server ad infinitum.


Re: Incoming Mail When Exchange Server Down by Mark

Mark
Thu Mar 06 19:43:32 CST 2008

On Thu, 6 Mar 2008 17:41:16 -0800, "Tom Bombadil"
<Genius_Poster@Yahoo.com> wrote:

>Thank you gentlemen for your replies.
>
>Mark, what you mentioned about ISP relays might be very reassuring to folks
>over here. I'd never heard of the concept before. Do you have any more
>information/links/articles on that? Thanks again!
>

Just call your ISP and work the words "fallback" and "SMTP" into the
conversation.

Re: Incoming Mail When Exchange Server Down by Tom

Tom
Thu Mar 06 20:55:40 CST 2008

Thanks Mark!

BTW, I posted a message in the Design newsgroup called Securing Exchange
Server. It'd be great if you could kindly have a look at it.


"Mark Arnold [MVP]" <mark@mvps.org> wrote in message
news:6d71t393uo6sl3734idlok17j2lqd3v9j1@4ax.com...
> On Thu, 6 Mar 2008 17:41:16 -0800, "Tom Bombadil"
> <Genius_Poster@Yahoo.com> wrote:
>
>>Thank you gentlemen for your replies.
>>
>>Mark, what you mentioned about ISP relays might be very reassuring to
>>folks
>>over here. I'd never heard of the concept before. Do you have any more
>>information/links/articles on that? Thanks again!
>>
>
> Just call your ISP and work the words "fallback" and "SMTP" into the
> conversation.