[MlMt] Duplicate messages in Sent Items (Exchange account)

[aisrael]

  I am not sure if it helps, but I found this message from 2022 (however 
it seems the raw headers of the pairs of mails were different in the 
reported case, which may not be your case)  :

This is a known issue: Mailmate moves the message from Drafts to Sent 
after you send it (that's the one with few headers), and then Exchange 
"helpfully" puts a copy of all outgoing mail into Sent as well. I have 
simply made a smart "In/Out" mailbox to show me messages where "From is 
not me" or "Received does not exist", which hides all of the Exchange 
copies.

Alain

On 3 Mar 2026, at 16:48, Jeff Bullard via mailmate wrote:

> I appreciate the response and that this is a cosmetic issue and not an 
> operational problem. Even so, I think the developer should be able and 
> willing to investigate and fix this, especially since the duplicates 
> do not appear within any other email client I have on my computer 
> (Apple Mail, Outlook, and Airmail).  It those apps all figured it out, 
> why not MailMate? Just saying it “is a known issue and can be 
> ignored” is not a very helpful response for those of us who are 
> experiencing it, especially since (a) Exchange is an extremely common 
> mail server and (b) some of us did pay at least a small amount for 
> MailMate.
>
> Jeffrey W Bullard PhD | FACerS | FWAS
> Department of Materials Science and Engineering
> Zachry Department of Civil and Environmental Engineering
> Texas A&M University
> 3136 TAMU
> College Station, Texas 77843
>
> On 3 Mar 2026, at 9:37, Robert Brenstein wrote:
>
>> This is a known issue and it has been discussed on this list a number 
>> of times. As far as I remember, the duplication is caused by Exchange 
>> server due to the way it handles sending mail. You can just ignore 
>> this duplication. Mail was sent only once. If you search past posts 
>> in the list, you may find how others go about this.
>>
>> On 3 Mar 2026, at 14:45, Luís Trevisan wrote:
>>
>>> Hi all,
>>>
>>> I'm experiencing duplicate messages in my Sent Items folder in 
>>> Microsoft 365 / Exchange account.
>>>
>>> Setup details:
>>> - Account type: Exchange / Outlook.com (Microsoft 365 corporate)
>>> - The duplicates appear exclusively in the Sent Items folder
>>> - The duplicate messages are identical
>>> - No other folders are affected
>>>
>>> Has anyone experienced this with an Exchange account and found a 
>>> reliable fix?
>>>
>>> Thank you in advance.
>>> Luís
>
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