When sending mass mails through IONOS mail servers, limits apply to prevent misuse (SPAM). Depending on your product, the following limits apply:

Mail Basic and Mail Business

The maximum number of emails you can send per hour depends on the following criteria:

  • How long ago the email account was created
AGE OF THE CONTRACT MAIL BASIC AND MAIL BUSINESS
0 - 7 Days 50 Emails per hour
8 - 14 Days 100 Emails per hour
15 - 30 Days 400 Emails per hour
> 30 Days 500 Emails per hour

If the limits are exceeded, the following error message is displayed:

Message could not be sent. Error message from mail transport server:
450 -
450-Requested mail action not taken: mailbox unavailable
450 Mail send limit exceeded.


Microsoft Exchange 2019

Maximum number of emails per minute through IMAP or POP3:

Age of the Contract Microsoft Exchange 2019
0 - 7 days 1 email per minute
8 - 14 days 2 emails per minute
15 - 30 days 7 emails per minute
> 30 days 10 emails per minute

Maximum number of recipients per day when sending emails through Outlook/Active Sync:

Age of the contract Microsoft Exchange 2019
0 - 7 days 1500 recipients per day
8 - 14 days 3000 recipients per day
15 - 30 days 12000 recipients per day
> 30 days 16000 recipients per day

Maximum number of recipients per email sent:

Contract type Number
Microsoft Exchange 2019 500 including CC and BCC (contact/mailing lists are counted as 1 recipient)

Google Workspace

Limitation Number
Emails per day 2000
Automatic forwarding of emails 10000
Email filter for automatic forwarding 20
Recipients per email 2000
Recipients per message via SMTP (POP/IMAP users) or the Gmail API 100
Recipients per day 10000
External recipients per day 3000
Individual recipients per day 3000