University Email Rejected by Gmail Due to Low Sending Domain Reputation (550 5.7.350)

Dr. Ghazy 0 Reputation points
2026-11-06T22:47:53.28+00:00

Dear Microsoft Support Team, I am writing to request your assistance regarding a persistent email delivery problem affecting my university email account, ******@agr.suez.edu.eg, which is hosted on Microsoft 365. I am a faculty member (Associate Professor) at the Faculty of Agriculture, Suez Canal University, Egypt. My academic responsibilities involve regular communication with international researchers, professors, universities, and research institutions. Unfortunately, my university email messages sent to certain institutional addresses, including university email accounts in Japan, are being rejected by Gmail servers with the following error: 550 5.7.350 – The message was rejected because the sending domain has a very low reputation. This problem is causing considerable professional and academic difficulties. It affects my ability to maintain research collaborations, communicate with international colleagues, follow up on academic opportunities, and conduct essential scientific correspondence. I have made several attempts to investigate the issue from the available Microsoft 365 administrative interfaces. Initial checks indicate that SPF is configured, while further verification of DKIM and DMARC configuration is needed. However, some administrative permissions and configuration settings appear to be managed centrally at the university level, beyond my current administrative access. I fully understand that the university may be responsible for managing its Microsoft 365 tenant. Nevertheless, I would sincerely appreciate Microsoft's direct assistance in the following matters: Investigating why emails originating from agr.suez.edu.eg are being rejected by Gmail due to low domain reputation. Verifying the domain's sending reputation and identifying any potential issues related to Microsoft 365 outbound mail infrastructure. Reviewing the relevant SPF, DKIM, and DMARC authentication configuration. Advising whether any action is required by Microsoft or by the university's central Microsoft 365 administrators. Guiding me toward the appropriate technical support team if this issue must be handled by the university's tenant administrator. I am not requesting access to administrative functions beyond my authorization. My intention is to obtain a clear technical diagnosis and ensure that this issue reaches the appropriate team capable of resolving it. I would be grateful if Microsoft could treat this matter with consideration of its impact on academic and international research communication. Thank you for your time and assistance. Kind regards, Abdullah Ali Ghazy, PhD Associate Professor Faculty of Agriculture Suez Canal University, Egypt University email: ******@agr.suez.edu.eg

Microsoft 365 and Office | Microsoft 365 Defender | Other | Windows

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  1. EmilyS_726 34,015 Reputation points Volunteer Moderator
    2026-11-06T23:27:30.05+00:00

    Hello

    This request needs to come from your university's IT department.

    It’s important to understand that Microsoft does not have the authority to manage individual users within an organization. Each organization’s IT department is responsible for managing its own users, following its own protocols and security policies. Microsoft’s role is to support the organization’s IT administrators by providing tools—not to bypass them or intervene directly.

    If Microsoft were to help you by bypassing the organization's IT admin user, it is considered a security breach.

    Please contact your IT department. They should raise a support request via Admin Center https://admin.microsoft.com > Support.

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  2. Dr. Ghazy 0 Reputation points
    2026-11-06T22:51:39.8766667+00:00

    Thank you for the detailed technical explanation.

    I would like to clarify that I am a faculty member and Associate Professor at Suez Canal University, Egypt, and I am also involved in IT support at the Faculty of Agriculture.

    Our university email domain is hosted on Microsoft 365. However, the administration of the Microsoft 365 tenant and its advanced Exchange Online settings appears to be centralized at the university level.

    I have already attempted to investigate the issue using the administrative access available to me, but I cannot access the required DKIM configuration and organization-level diagnostic tools.

    This issue is particularly serious for my academic work because it affects correspondence with international universities, research collaborators, and academic institutions.

    Could a Microsoft employee or an Exchange Online specialist please clarify whether this rejection could be related to the sending domain's reputation or Microsoft 365 outbound infrastructure, and whether there is any way for an affected faculty member to request a technical investigation directly from Microsoft?

    I would appreciate specific guidance on how to escalate this issue when the local faculty user does not have access to the university's central Microsoft 365 administration.

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  3. AI answer

    2026-11-06T22:49:02.42+00:00

    The university’s central Microsoft 365 administrators must investigate and remediate this issue because the NDR shows that Exchange Online transferred the message successfully but Gmail rejected it based on the sending domain’s reputation.^1^

    This is not something a mailbox user can correct through Outlook, and the error by itself does not establish a Microsoft 365 outbound-infrastructure fault.

    What to send to the university administrators

    Provide the administrator with:

    • The complete non-delivery report (NDR), including Diagnostic information for administrators.
    • Sender and recipient addresses, redacted where appropriate.
    • Date and time, including time zone.
    • Message ID or Network Message ID, if shown.
    • Confirmation of whether all Gmail/Google Workspace recipients are affected or only particular institutions.
    • A recent rejected message sent without attachments or links, if available.

    Ask the administrator to perform these checks.

    1. Confirm the rejection in Message trace

    In the Exchange admin center, run Mail flow → Message trace for the sender, recipient, and failure time. Message trace identifies whether Exchange Online delivered, deferred, or rejected the message and records the events leading to its final status.^2^

    The expected result in this case is an outbound message handed to Google, followed by Google’s remote 550 5.7.1 reputation rejection. If trace instead shows a Microsoft restriction or outbound-spam action, investigate that separate tenant-side condition.

    An administrator can also retrieve trace details through Exchange Online PowerShell:

    $sender = "[Email]"
$start  = (Get-Date).AddDays(-2)
$end    = Get-Date

Get-MessageTraceV2 -SenderAddress $sender -StartDate $start -EndDate $end |
    Get-MessageTraceDetailV2

    2. Validate authentication for the exact sending subdomain

    SPF being present is not sufficient. Microsoft recommends configuring SPF, DKIM, and DMARC, in that order, for every custom domain and subdomain used to send mail.^3^

    For the exact domain appearing after @ in the From address, the administrator should:

    1. SPF: Verify that there is only one SPF TXT record and that it authorizes every legitimate sending service. Each defined sending subdomain requires its own SPF record; a parent domain’s SPF record does not cover it.^4^
    2. DKIM: Obtain the two domain-specific CNAME values from Microsoft 365, publish them in DNS, and enable DKIM signing for the custom domain. The signing domain should align with the domain in the visible From address.^5^
    3. DMARC: Publish DMARC only after SPF and DKIM are configured. Start with p=none and reporting, review legitimate sources and alignment failures, and then move gradually to p=quarantine and ultimately p=reject; applying enforcement without testing can reject legitimate mail.^6^
    4. Inspect the receiving copy or test-message headers for Authentication-Results. At least SPF or DKIM must both pass and align with the From domain for DMARC to pass.

    These DNS and tenant changes require the university’s DNS and Microsoft 365 administrative access.

    3. Check for activity that damaged domain reputation

    The administrators should review:

    • Unusual outbound volume or messages the faculty member did not send.
    • Compromised accounts, suspicious inbox/forwarding rules, and unauthorized applications.
    • Tenant alerts named Suspicious email sending patterns detected, Email sending limit exceeded, and User restricted from sending email.
    • Exchange mail-flow reports and message traces for other accounts sending through the same domain.
    • Bulk-mail systems, websites, laboratory applications, or third-party platforms using the university domain without aligned SPF/DKIM.

    Microsoft documents these reports and alerts as the tools for detecting abnormal outbound activity.^7^

    If bulk or newsletter mail is being sent from the university’s primary domain, it should be stopped temporarily and later isolated on a properly authenticated subdomain. Microsoft 365 does not support bulk email beyond best effort, and bulk activity on a primary domain can affect ordinary mail delivery.^8^

    Immediate workaround

    For urgent correspondence, contact the recipient another way and ask their Google Workspace administrator to allow the specific sender or university domain. This can restore delivery to that institution, but it does not repair the domain’s general Gmail reputation.^1^

    Escalation to Microsoft

    If authentication passes, no compromised or bulk-sending activity is found, and Message trace suggests a Microsoft-side routing or outbound-pool problem, a university Microsoft 365 administrator should open a service request:

    1. Microsoft 365 admin center → Help & support.
    2. Enter the error and affected domain.
    3. Select Contact Support.
    4. Attach the full NDR, message-trace results, timestamps, message IDs, and authentication headers.

    Only an administrator for the organization’s business subscription can use this support route. If the university purchased Microsoft 365 through a partner, that partner is the support contact.^9^

    References

    1. Email send receive issue - Microsoft Q&A
    2. Trace an email message in Exchange Online
    3. Get started with Microsoft Defender for Office 365
    4. Set up SPF to identify valid email sources for your custom cloud domains
    5. Set up DKIM to sign mail from your cloud domain
    6. Set up DMARC to validate the From address domain for cloud senders
    7. Troubleshoot outbound sending limits and blocked users in Exchange Online
    8. Outbound spam protection for cloud mailboxes
    9. Get support for Microsoft 365 for business
    AI-generated content may be incorrect. Read our transparency notes for more information.

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