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We are faced with a dilemma with using snow leopard. We want to have thr snow leopard server on site and not off site because it makes sense to have the server in the network physically for other services (file sharing, VPN, wiki etc) but our office does not have a very reliable Internet connection so it'd hard to host the email with it. We don't want to factor out the email as a separate server because we want to enjoy a single user login across everything. How do we get around this dilemma?

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migrated from superuser.com May 29 '10 at 22:12

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Honestly, hosted Exchange has become so inexpensive now that for small and mid-sized businesses it almost doesn't make sense to host locally. This makes even more sense if you don't have a reliable connection. –  MDMarra May 21 '10 at 22:01
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Not even hosted Exchange, a hosted SMTP/POP or IMAP mailbox would be good enough. –  ta.speot.is May 21 '10 at 23:39
    
@taspeoris - That's true, vanilla mail hosting is dirt cheap. I recommend exchange to everyone though for the calendar/meetings/contact integration. –  MDMarra May 22 '10 at 3:59
    
You're assuming that their clients are Snow Leopard and later. And also, aside from the Mail App, I have found hosted Exchange doesn't work well with Snow Leopard and Address Book/Calendar, despite ActiveSync being a "standard". If you're on a Windows stack I think hosted Exchange is fantastic. I use SherWeb and only had 1 small issue with them (it was a billing issue, and it was a gray area as to whether it was me or them at fault). –  ta.speot.is May 22 '10 at 7:42
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4 Answers

If it's a given that the Internet connection at your office is unreliable, you'll probably run into any or all of the following problems:

  1. I assume your Snow Leopard Server will be the the MX for your domain. If that's the case, if a foreign MTA tries to send mail to your domain while your connection is down, obviously it won't get delivered. This happens occasionally, so most MTAs are configured to retry sending the messages for between 3-7 days. If your network comes back up for a good amount of time before 3 days, you can be reasonably sure your messages will get delivered. Your users may not be happy it took so long, though.

  2. If your network is down, your users will not be able to send mail. You can partially combat this if you have an external SMTP server your users can authenticate to and allows sending mail from your domain. Obviously if the office's network is down even this won't help, but home users and cell phones with email can benefit.

  3. If your network is down, users won't be able to access their email from home or from their phones. If your mail server is behind a downed network connection, there's not really a solution to this.

None of these are particularly fun problems to deal with. Two solutions I can see:

  1. Upgrade your office's Internet connection; talk to the ISP and demand they figure out why your connection is so unreliable. You'll probably need to do this anyway eventually; no one appreciates a flaky Internet connection. If you're paying for a business-class connection, you should expect business-class reliability. If you're trying to run an office on consumer-grade hardware or service, upgrade. I realize this may not be possible, but I think delivering reliable, business-class email demands a reliable Internet connection.

  2. Outsource your email services. This won't fix your flaky office connection and you'll lose the single sign-on, but given the choice between delayed, unreliable email and maintaining a second password, I think most users would prefer the latter. Many business users assume email is sent instantaneously and they plan their workflow around this assumption; if email takes days to deliver, their ability to work is severely hampered. Obviously, the extent of this depends on your users and the business. They'll also get cranky if they can't access their calendars and address books. Hosted Exchange solves all of these problems.

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You probably don't need to worry about incoming SMTP email that needs to get to your mail server, because if you have a savvy ISP, they may be able act as your backup mail exchanger (MX) to buffer incoming SMTP email for you while your internet connection is down. If your ISP isn't so savvy, you can use a service like MXSave.com as @taspeotis pointed out. When your connection is back up, your backup MX at your ISP or at a service like MXSave will make an SMTP connection to your Snow Leopard Server and unspool all the mail that it had queued up.

Also, don't worry about offsite users being able to send email while your internet connection is down. They can use their own home ISP's SMTP relay for that.

The only real concern would be that your offsite users would be unable to read their new messages via POP or IMAP while your internet connection is down.

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First, you are wrong. Secondary MX records work that way, but the ISPs mail server will probably discard the email because it's authoritative for the domain, but won't forward to the primary MX record (why? The mail has already been delivered to the mail server you specified). You need something like MXSave which is designed for this. –  ta.speot.is May 21 '10 at 23:36
    
Second, you're assuming their ISP allows relaying for arbitrary domains, this is 50/50 at best. Most home ISPs will limit mail sending only from their domain, they don't become open relays with authentication. –  ta.speot.is May 21 '10 at 23:38
    
@taspeotis Thanks for your feedback. I've tended to use savvy local ISPs that have been happy to provide backup MX service for my domain, and who know how to configure their mail servers to accept mail for my domain without considering themselves the ultimate endpoint. I'm sorry to hear that this isn't a standard feature of other ISP's business class broadband packages. I'll update my Answer to better reflect that. –  Spiff May 22 '10 at 4:51
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People like the guys behind macmincolo are a demonstration that reliying on macminis and building your own server is good and enjoyable. Setting up everithing you need on Mac OS X server appear less easy but at the end doable. AFAIK you can roll out you own Postfix installation on MAC OS X if you don't want to go with the server. You can have also PUSH notification services. This guide here has a fair amount of info to build your own ISP in a box @home, and the chapter about the mailserver seem to be what you need.

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Two things in response; firstly - having an intermittent network connection for your mail server can be a minor to major annoyance for SMTP services.

From the internal (your users) sending mail perspective, its a very mixed bag. Your local SMTP server will queue up the mail, find it can't send it - and wait around for awhile before trying again and again - hopefully eventually making it out. This gives them the impression that the mail was sent which keeps them from calling you at 2AM (my mail won't send!) but also causes them to expect the recipient to immediately receive the message (I sent the purchase order an hour ago! Why do they pretend like they never got it?!).

Flipping things around, its also bad for an external user trying to send mail into your users. They will (generally) get the feeling that the message was sent, even though it might not have been. This can cause some irate conversations when your company fails to act on something that people feel should have been acted upon.

Now, if your internet connection is flaky and you go with an outside hosted solution, your users will still be annoyed. They will likely get an error message from their email client when attempting to send. At least with your internal server, it gets gladly accepted and queued up.

Email's a funky thing, if its not split-second responsive and 100% reliable - you (as an admin) will see no end to complaints from your users. Its also generally considered 'business critical' that it work perfectly without hiccups - even though its usually used for sending photos of the boss' kids.

Both ways of getting mail out of your network have quirks if your internet connection is flaky. Internally hosted, it'll get queued and delayed such that your users will occasionally be cranky when they see it took an hour for an email to go through instead of 1ms. Externally hosted, your users will get error messages and be very cranky all the time.

Its a lose-lose situation with an unreliable ISP link. I hate deflecting questions like this, but for something so perceived-as-critical as email - it must be perfect. Without a reliable internet connection, it never will be - and you'll be the bad guy.

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