3aIT Blog


Outlook (various versions) seems to hit a problem when sending large emails. If an email sending takes too long (slow network, large attachments, etc) then outlook seems to assume it failed and will try to send the email again. However, the original email is still sending. This process repeats, causing the same email to be sent multiple times.

Whilst stuck in the loop, any subsequent emails sent, even if they aren't large, will also get caught up and get sent.

The solution is to extend the amount of time Outlook will wait until it deems the sending to have failed. The default is 1 minute, so extending this to 5mins should do the trick (although under normal circumstances, of course, if an email is so large it takes longer than 5 minutes, it probably shouldn't be sent via email).

This setting is the 'Server Timeout'.

(For the purposes of this blog, we'll be using Outlook 2010. Other versions of Outlook will be similar, but with slightly different way of getting to the 'Account Settings' window).

  1. Click on the orange 'File' tab.
  2. Under the 'info section, click on the 'Account Settings' button and then on the 'Account Settings...' option from the menu. The Account Settings window will open.
  3. Under the 'E-Mail' tab, find the IMAP account affected, select it and click on the 'Change...' button (or double-click it)
  4. Click on the 'More Settings...' button.
  5. Under the 'Advanced' tab you will find the 'Server Timeouts' option.
  6. Move the slider towards the right (long) to the desired value (5mins?)
  7. Click OK and close all the windows.

# John Oosterman 2015-08-06 11:13
Advice seems to work!!!, Many Thxxxxxxxx
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# Mark Lawrence 2015-10-30 06:24
in outlook 2016 the more settings button is not available on an exchange account. I want to do an outlook 2016 server timeout change as I am getting doubled up attachments and email addresses. This was the fix in 2013 but it is not there in 2016
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# hassan 2015-11-04 05:48
thank you very much for these information
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# simon 2016-02-23 11:14
This work for us.Thank you for your advice
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# Christine 2017-07-06 10:54
Really appreciate your Advice. Worked for Outlook 2016. Sent straight away.
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# Gerard 2018-04-25 09:56
That is super, thanks! This has been such a problem for us and we have been looking for a solution for a while.
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# aaaa 2018-08-05 13:47
Is it possible to do the same thing on android mail clients ?
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# 3aIT 2018-08-06 08:23
There are many Android mail clients, so the answer is almost certainly yes on some of them. The default Android client is pretty basic though, so if you're using this and having problems, it may well be worth trying an alternative app.
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# aaa 2018-08-06 08:55
Thanks alot for your reply ,Can you please name one or two android mail client that I can adjust its timeout settings ?
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# 3aIT 2018-08-13 09:06
I've just had a quick look around and haven't found a client that advertises this feature. It may be worth trying a few and seeing if one of them solves your problem. I use K9 Mail myself, and have never had a problem like this.
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