Warning: Your iPhone or Mac Mail May Be Killing Your Website

I recently discovered something very important for WordPress sites hosting with Hostgator’s shared option and I wanted to share it with our readers. However, this doesn’t apply only to WordPress sites and Hostgator – it’s a general warning for any site on shared hosting. Your site may be at risk if the email is hosted on the same server as the website.

Primary Symptom: Nasty 500 Errors

If you’re continually getting 500 errors when visiting your site, then one possible cause is that you’ve exceeded the number of concurrent processes allowed by your host. This is one that will continually slip past your error logs.

The Problem with Mac Mail and iPhone email

The iPhone and Mac Mail are notorious for keeping processes open when checking the server for mail. On the iPhone there is a function called “push” and when it is enabled, it keeps the connection to the server open and continually checks mail. Consequently, this creates many IMAP processes, even for the same email address.

The main problem with Mac Mail is when it’s on the IDLE setting. This basically leaves the connection to the server open to check for new messages as soon as they arrive rather than trying to connect every 5 minutes or so.

Please note that this may also apply to other hosts, but I know it’s Hostgator’s explicit policy to deny service when processes exceed 25 per account, which results in 500 errors. – this would include any kind of connection to the server, such as FTP and plugins on your site that start internal processes, plus email connections. The processes can really add up if you’re not careful, especially when email connections are left open.

The resulting 500 errors can literally cripple your website.

If you’re experiencing this, check to see how many processes your host allows to run simultaneously. It’s usually different for each host. For example, 1&1 shared hosting packages currently allow for 16 simultaneous processes. BlueHost limits IMAP connections to 20 at a time. Site5 only allows for 5 processes at one time.

3 Solutions to Help Reduce 500 Errors

Here’s what you can do. Selecting any one of these options should help to drastically cut down on your 500 errors and will in many cases fix your problem entirely:

1. Reconfigure your Mac Mail and iPhone email clients according to the instructions here:

If you have hosting with Hostgator, follow the instructions below for making sure your email is set up correctly.


You can also try setting up Z-Push, an open source activesync protocol that allows users to sync contacts and calendars to multiple devices using PHP.

2. Forward all of your domain mail to Gmail or Thunderbird or another email provider.

If you’re using Gmail or the like to handle your email, then you’re not opening processes on the server at all. You free up your processes for your website to use.

3. Switch to VPS Hosting

Sure, shared hosting is okay for small, low traffic websites. However, the online face of your business depends on visitors being able to access your website at any time without issues. VPS hosting generally does not have a limit on the number of processes you can run at one time, so chances are that you’re less likely to overload.

The bottom line is, if you’re on shared hosting, make sure your mail client is configured correctly in order to ensure that your site has the most resources possible available. The last thing you want is for your website’s visitors to get 500 errors simply because you’ve been reading chain emails from your Aunt Hilda on your iPhone. If you have to stick with shared hosting for budget reasons, then apply one of these fixes to make sure your website has the resources it needs.

17 Responses

  • I just had this EXACT thing happen on 4 websites hosted at Hostgator along with their emails. They were all using iPhones, Apple Mail and some on MobileMe. The running processes were through the roof and it took down the sites multiple times a day. We upgraded them to VPS hosting which was another pain in itself. I hate how Hostgator has unlimited everything EXCEPT running processes. They need to fix something with Mail and iPhones because this must be a common problem for them.

    • This is not just a problem with Apple (Mac Mail, iPad, and iPhone). I use Thunderbird and my Android device to read my hostgator email and this still happens approximately once per week. I have to change hosting providers; I can’t have my site going down like this all the time.

  • WPMU DEV Initiate

    I opted for the hosted Gmail option. First time I ever did it myself, I’ve had help or looked over the shoulder of people doing it.

    Start to finish, including configuring the mail accounts, settings and setting it up in Sparrow (my fav Mac mail application) was about 20 minutes… Worth doing.

    Thanks for this tip. Not sure if this is the cause of my recent 500 errors, but at least now I can cross off this on my checklist…

  • Hi Sarah,
    A similar issue also seems to happen with a Blackberry configured to use IMAP.

    I have a client hosted on my server whose Blackberry holds an IMAP process open for ever.
    It’s only one process, but my security configuration alerts me after a process has been running for an hour, thinking something may be stuck or suspicious. It then continues to email me every hour about the same problem!

    At first I added an exception to the security rules, allowing it to run for 24 hours, but then realised it runs longer than that, in fact, continually.

    In then end I set up a cron job to kill the process a couple of times a day. It does no harm and the Blackberry just reconnects straight away, just like it would if it lost the signal.

    If anyone gets similar warnings about long running or suspicious process, check your Blackberry.


  • New Recruit

    This is not a problem for all shared hosting, just some. The problem is when you host on unlimited sites, they have to have some limits so they hide them. Other hosting companies do not limit based on processes, so be sure to check with your provider. So please dont blame all shared providers as your

    it’s a general warning for any site on shared hosting. Your site may be at risk if the email is hosted on the same server as the website.

  • Thanks for this post!

    I have just checked with my hosting provider and they have separate maximum connection limits for email, ftp and web access.

    Their limit on for example emails is 4 concurrent connections per server accessed from a single IP address. If I say setup 5 email accounts (where all email accounts are hosted on the same server) on my iPhone, their limit will kick in when I sync my emails simultaneously from my iPhone. My iPhone will ask me to check my passwords which are correct, but will sync manually next time.

    The above applies for both shared and dedicated servers.

    This will not impact my main site in any way since a separate maximum applies for my site.

  • This is why I don’t host with the “big box” hosts. Any host worth their salt won’t keep an email server on the same box as a shared web server. I’ve hosted my WP sites and email with Valice for years, and this has never been a problem for me. I have shared and VPS WordPress projects with them, and email has never interfered with web performance.

  • We experienced this exact same issue. We had several users using IMAP email in Outlook, iPhone and iPad. We were running too many processes and constantly causing 500 errors. Not good. We immediately moved to Hostgator’s VPS hosting and it has been fine ever since. Thanks for the great article.

  • Interesting. I”ve had lots of problems with godaddy and wordpress and i wonder if this issue of concurrent processes is part of that problem.

    i did call them and found they offer 50-300 processes depending on what kind of account you have. see:

    Linux Economy: 50 connections
    Linux Deluxe: 100 connections
    Linux Premium/Unlimited/Ultimate: 200 connections
    Windows limits are similar

    4GH (ALSO CALLED “GRID”) accounts allow many more connections. This number varies, but is at the following minimum amounts:

    Linux 4GH limits:

    Linux 4GH Economy: 150 connections or more
    Linux 4GH Deluxe: 300 connections or more
    Linux 4GH Premium/Unlimited/Ultimate: 600 connections or more

  • The other way to handle this issue is to use the push mail accounts settings on the iphone.

    To adjust the push or fetch settings for push or email or other accounts on iPhone or iPod touch, tap Settings from the Home screen and then choose Fetch New Data.

    Here is the url to show you screen shots of what it looks like.
    This resolves the issue of the email account constantly checking the server for email.

    When you click on the mail icon on your phone it will then check for email if you set it up to MANUAL instead of fetch or push.

  • Or you can just tick off the IDLE option in the settings. There’s a “use IDLE command if the server supports it” in the mail advanced settings.

  • New Recruit

    This is a total outrage on the part of Hostgator. It is *not* an Apple, nor any other mail client’s fault. Its totally shitty service from Hostgator which claims to offer a great plan with unlimited domain hosting yet then imposes this utterly ridiculous limit on mail connections. I sync IMAP mail on a smartphone, tablet, and one laptop and my domains on Hostgator are constantly down because of the “Internal Server Error” problem. I strongly advise everyone DO NOT USE HOSTGATOR. Find another hosting provider like Dreamhost which does not mislead customers and impose outrageous, draconian limits on mail connects which KILLS all hosted web sites.

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