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

[Henry Seiden]

If it has been the case this long, pretty sure Benny, the developer has known about it as has M$ (Microsoft). As to why they each made that conscious decision is up to the respective developers, I’m betting it was a conscious one on each of them. Mailmate shouldn’t be responsible for unique non-standard server’s, that’s a slippery slope in my opinion.

It is easily avoidable on the users’ end, regardless.

Respectfully,

Henry Seiden
- -
Techworks Pro Co.
E: info<at>techworkspro<dot>com
W: http://techworkspro.com

On 3 Mar 2026, at 11:21, aisrael wrote:

> 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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