[SOLVED] Obtain max allowed message size for M365 user

Obtain max allowed message size for M365 user

I'm trying to figure out if I can use EWS or Graph to obtain, for a given user, the maximum allowed message size (as configured by the administrator). I'm using direct http calls, not the managed API. There is a lot of information I can obtain about users in the mailboxSettings resource, but that property does not seem to be one of them. Any help appreciated.

Solution

Its not exposed directly but you can use the MaxMessageSize MailTip (as long as they are enabled) for a mailbox which should return the max message size (mailbox or org depending on which is lower) eg

https://graph.microsoft.com/v1.0/me/microsoft.graph.getMailTips

{
    "EmailAddresses": [
        "user@domain.com"
    ],
    "MailTipsOptions": "maxMessageSize"
}

ref https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/mailtips/mailtips