Windows Outlook sents an email 10 times repeatedly, once a minute. IMAP/SMTP protocol

Question

On windows version of Outlook, using IMAP/SMTP to connect my own email backend service, a email was sent 10 times repeatedly

As I saw on my backend log, each SMTP connection was execute successfully and quit normally. The network is stable to transmit 20M file in 20 seconds. All configurations are default.

I wonder what would cause outlook to keep retrying?

Time: May 25, 2023 around 19:00 GMT + 0800 unixtimestamp 1685012601

First time

AUTH: 19:03:21.684

Reading DATA starts at 19:03:22.658

Read DATA end: 19:03:31.622 (+ 9s)

DATA success: 19:03:43.408 (+ 12s)

QUIT: 19:03:45.928

Second time

AUTH: 19:04:24.876

Reading DATA start: 19:04:25.889

Read DATA end: 19:04:38.352 (+ 13s)

DATA success: 19:04:50.357 (+ 12s)

QUIT: 19:04:51.989

...

Tenth time

AUTH: 19:12:25.492

XCLIENT: 19:12:25.531

Read DATA end: 19:12:42.628 (+ 16s)

DATA success: 19:12:54.597 (+ 12s)

QUIT: 19:12:57.457

Answer 1

Hi @Ariacx ,

Welcome to our forum!

Does this issue occur with all emails you sent or the specific email?
And does this issue occur recently? If so, have you done any specific operations before that?

Considering the impact of some add ins, It is suggested that you try to start outlook in safe mode (win+R>type: outlook /safe) to check whether it works normally.

If the issue persists, in order to confirm if the corrupted Outlook profile is damaged, it's suggested that you could create a new Outlook profile and add your IMAP account to check if there're any differences.

If the above doesn't help, based on my research, i found that the issue may be related to virus scanner. It's suggested that you could refer to this article and try the suggestions mentioned in it:

Outlook is sending multiple copies of an email
(Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)

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