For this question, let's assume I needed to send an important email to a potential customer. Because of a problem with my email client, which rarely happens, two copies of the email are in my Sent folder (both there and on my webmail client). It looks like the message has sent twice, although I'm not 100% sure about that because I can't see the recipient's inbox.

I am wondering if I need to send another email to apologize for this or if that would just be adding more noise to this person's inbox. Is there a business/workplace etiquette convention for this?

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    Comments are not for chatting; this conversation has been moved to chat. Yes I know many of them are funny and some highly-voted, but take it to chat please. We won't be able to move additional comments to chat, so expect those to be deleted if they aren't about improving the post. Mar 17, 2016 at 17:56

6 Answers 6


Only send another email to the receiver if it would be something that they would worry about, for example an email saying "thank you for your order, and we will bill $2,345 to your account" - if I received that twice, I would be worried that you might bill me twice.

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    A very valid point, if there's something specific like this it's worth just going "Sorry, I sent that email twice by mistake... don't worry, you'll only be billed once!" or similar
    – Jon Story
    Mar 17, 2016 at 15:45

No, leave it as-is.

In situations like this do a quick analysis of the benefit of doing/not-doing the activity.

  • Benefit: Clarity on the emails sent, sensitive to client
  • Downside: More emails in inbox, appearing over-apologetic, possibility that the client didn't actually even receive double emails.

Then critique the benefits:

  • Clarity on the emails: If I sent two identical emails at the same time I would assume that there was a IT error. Over-apologizing can also come across as self-deprecating, unprofessional, annoying or incompetent where it is unnecessary.

You should then be able to arrive at a sensible outcome by weighing up the benefits and the losses.

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    +1 especially for the last bullet. Not only are you wasting someone's time explaining something that didn't need explaining, you're needlessly drawing their attention to the fact it was you, and not some IT glitch, that made a minor mistake. Mar 18, 2016 at 13:15
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    Also, what if the apology mail also gets sent in duplicate?
    – rest_day
    Mar 18, 2016 at 13:35
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    Another benefit could be to save the recipient the effort of comparing the two e-mails. This is especially the case if it's a lengthy, detailed message where the recipient might be concerned he's received two versions with potentially unique important bits in either one.
    – Mels
    Mar 18, 2016 at 15:22

I wouldn't worry about it. They'll clearly realize it's a mistake and ignore one of them.

Problems would only arise if some subtle detail was different in one of those messages.

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    Yes, but some people will be driven to distraction trying to decide which one to ignore.
    – JDługosz
    Mar 16, 2016 at 23:52
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    I would compare them, and reply to the one with more favourable conditions. Mar 17, 2016 at 10:58

As long as you're sure that two e-mails you have sent are verbatim copies, there's no need to apologize. This happens quite often and any reasonable person should be able to discard the duplicate e-mail quite quickly, if it's not discarded automatically by their server or messenger. You'll actually waste more of your client's time by writing them an apology.

If there's a chance that two messages are even slightly different, you should write a follow-up, telling which message is the right one. Even a small difference (like adding "RE:" to the subject line or changing the signature) can be confusing. It's even worse when an important detail is missing (attachment, approval line) but the messages look identical otherwise.

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    As a recipient I would prefer to get a notice that the sender was aware of the error so I don't have to worry that there's some difference between the apparently-identical emails which I might need to account for. Mar 16, 2016 at 19:37
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    @R.. If you have an alternative answer, please post it as an answer. At this time none of the answers suggest your approach, so adding yours as an answer seems reasonable.
    – user
    Mar 16, 2016 at 20:20
  • @MichaelKjörling: Indeed, that's a good idea. Done. Mar 16, 2016 at 21:02
  • If the message was sent twice, each of the messages would have a different Message-ID and would never be discarded by the email system (for the system these are different messages, it does not analyze their content)
    – WoJ
    Mar 19, 2016 at 20:05

As a recipient, I would prefer to get a notice that the sender was aware of the error so I don't have to worry that there's some difference between the apparently-identical emails which I might need to account for. Something like the following would be great:

A quick heads-up: my mail software may have sent you two copies of that last email titled [...]. They should be identical and you can just disregard one of them. Sorry for the noise.

Of course it could be adapted to be less/more casual as appropriate for the recipient.

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    +1, I suppose it depends on the contents of this exact email but this would be my preferred course of action for an "important" email if I was the recipient. Otherwise I'll spend time reading both emails to make sure they're the same.
    – Dan C
    Mar 16, 2016 at 21:04
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    Exactly. In my case emails often contain patches and I'd be wondering if they'd just accidentally sent the patch twice or noticed an error, fixed it, and resent. :-P Mar 16, 2016 at 21:06
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    As a recipient getting duplicate messages from time to time, I have a plugin which automatically discards duplicates. This approach requires 0 time on both sides to correct the error, and is also more reliable than manual check for differences. Mar 17, 2016 at 7:47

(If you use Outlook or a mail client that supports message recalling)

You can recall the second message (you can also add a message along the lines

Please accept my apologies - I sent this message twice by mistake. You can discard this copy

You also have the option of attempting to delete unread copies of the duplicate message, so in some cases if they haven't read it, they never even see it.

In other cases it can replace your duplicate e-mail with your message, so in either of these scenarios you don't get a third message, you just get your mess tidied up and explained.

This completely avoids any confusion because the receiver might assume there is a difference between them and the second one differs to the first.

It also avoids you having to lie and say the server must have sent it twice, which might prompt someone to start investigating why this happened.

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    I personally would be more annoyed by a third apology email, and would automatically assume that there was a technical issue or that it was an accident if I received the same email twice.
    – kirsty
    Mar 17, 2016 at 12:20
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    Recalling a mistakenly sent email is clearly the best option if possible. You even get feedback stating if the recall was successful or not!
    – wnnmaw
    Mar 18, 2016 at 13:33
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    "The recall feature in Microsoft Outlook tries to stop delivery and, optionally, replace an email message that you have already sent to another Microsoft Exchange Server user within your organization." - this is clearly not the case here. No way (thankfully) to recall a message sent to another server once it is received. Mar 19, 2016 at 17:43
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    Recalling messages does not work reliably. Where I work we use Outlook, and when someone tries to recall a message all I see is an email stating they would like to recall it. I always laugh at this, it draws attention to the email they wanted to retract, without actually retracting it.
    – Josh
    Mar 20, 2016 at 4:31

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