It is generally a good idea to deliver important communications, such as a rent increase notice, in person if possible. This can help to ensure that the message is received and understood, and can also give you the opportunity to address any questions or concerns the tenant may have.
One option you could consider is scheduling a time to meet with each tenant individually to deliver the notice and discuss the rent increase. This can be done either in person at the fourplex or through a virtual meeting, depending on your preference and the tenants' availability. You can text or email the tenants to schedule a time for the meeting, explaining that you have an important notice to deliver in person.
Alternatively, you could try to find a reason to visit the fourplex for a non-rent related issue (such as a repair or maintenance issue) and use that opportunity to deliver the rent increase notice in person.
It is important to remember that you are required to follow all relevant laws and regulations when increasing rent, including any notice requirements that may apply. Be sure to familiarize yourself with these requirements before proceeding with any rent increases.