The dangers of sending bulk email

Did you know that there are limits on the number of emails that can be sent from a Microsoft 365 mailbox? Many users may not be aware of the fact that sending bulk email is not a supported use of Microsoft’s service.

What happens if I try to send bulk email from my Microsoft account?

Some points to consider:

  • The “to” line in your email can’t show multiple addresses across various organisations. This would constitute the sharing of personal data, which is in breach of GDPR.
  • If you use the “BCC” line instead, then although recipients won’t be able to see other recipients’ email addresses, the mail could end up in junk folders.
  • If you exceed Microsoft’s limits for bulk email (see below), then as well as stopping the mail from being sent, Microsoft may block your account and the accounts of all other users in your organisation meaning that none of you can send any mail for around 24 hours.

The reason for this is to protect the service from activity initiated from compromised accounts, and to protect recipients from bulk email senders that haven’t legitimately obtained their mailing lists.

There is also a concern on Microsoft’s part that their 365 email servers might be put on third-party blocklists – thereby putting the service at risk.

The published limits for bulk email are:

  • 10,000 sent email messages per day
  • 500 recipients in total, for a single email
  • 30 emails sent per minute.

However, there are some other factors which can restrict the volume, including the number of characters in email addresses.

What should I do instead?

If you need to send the same email to numerous recipients, there are several software packages designed specifically for this purpose. In return for a monthly subscription you can design and send mass mail, newsletters and other communications, whenever you need to.

Talk to us to find out more, or enter your contact details here.