In online surveys, two general email invitations to all units are usually sufficient (the second invitation is also a thank you to the respondents).

In the case of a smaller number of units (eg a few hundred) we use the default email system (eg Gmail, Outlook ...), and if there are more units, we use mass sending tools (eg SqualoMail, MailChimp ...).

A large number of invitations and following the respondents is mostly unnecessary, but also demanding.

Email invitations can also be sent via the 1KA system, both general and individualized invitations with code and tracking. In addition, 1KA supports (documents) the sending of invitations by mail, SMS, etc. "