Mail to a distribution group doesn't reach some members
Distribution groups 'expand' to individual addresses. If one member bounces, it can disrupt delivery to the whole group.
Try this first
- 1Run message trace for the group, inspect individual expansion
- 2Identify which members bounce or stall
- 3Remove dead addresses from the group
- 4For large groups: switch to dynamic group or M365 group
When to bring us in
On old on-prem distribution groups, consider migrating to M365 Groups.
See also
- Our emails land in spam for some recipientsAlmost always an SPF, DKIM, or DMARC setting that is wrong or missing, or a sender name that mimics a well-known brand.
- Someone reports receiving phishing emails "from us"Read: spoofing. Someone is abusing your sender name, not necessarily your actual mailbox.
- An email bounces (NDR): delivery failedThe NDR text usually states the exact reason. Reading it is step one.
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