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IMAP request limits?

Julien CHAVEE 1 Reputation point
2021-07-22T17:47:59.73+00:00

Hi,

We have a PHP application that connects on an M365 email address via IMAP.
Sometimes, our PHP worker is completely frozen, doesn't respond to any kill command (except kill -9 of course).

From the network side, we can see that the TCP connection is established, and from debugging tools, our application is waiting in "READ" mode on the socket (forever, no timeout is working even if its set).

When we kill the worker and restart it, it works again (for few minutes/hours) until freezing again.

What we are wondering, is there any request limit (X requests per min/hour/day/...)? Does Microsoft temporary "blacklisting" us? Anything else...?

Thanks in advance for your help :)

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  1. Julien CHAVEE 1 Reputation point
    2021-07-23T11:37:01.83+00:00

    Hi,

    Thank you for the answer.
    We do not send any email via our PHP application. We only connect, search emails (by subject, sender, receiver, body content) and fetching attachments from emails.
    We also move emails.

    Is there any limitations on this part? I checked the linked you gave me but I can't see anything related to this part.
    Is there any explanations why the opened TCP connection do not receive anything from Microsoft's server? Sometimes we are receiving "Warning : imap_open(): Couldn't open stream {outlook.office365.com:993/imap/ssl/novalidate-cert}" but most of the time the socket does not receive anything that could indicate we can't connect.

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  2. KyleXu-MSFT 26,406 Reputation points
    2021-07-23T07:45:41.36+00:00

    @Julien CHAVEE

    Here are the limitation about sending emails:
    117319-qa-kyle-15-44-51.png

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