I know that you are probably blanking out GDPR information but this is not just general advice but a specific suggestion around Sole Traders and Partnership records that you hold on your database as they are to be treated as individuals and therefore different rules apply.
Can you identify who they are on your database? You will need to know, in order to comply.
The rules around email marketing to these people are that you must have consent. The soft opt-in will not apply unless you have a contractual arrangement with these contacts. This means that they have paid for something/ are negotiating to pay for something and not just attendees of a free event for example.
Legitimate Interest is not valid either in respect to these individuals and the offer to opt-out previously is not enough, they must have opted in.
You can however call these contacts as long as they have not opted out. Therefore it is worth considering a telemarketing campaign to get consent from this element of your data. Or at least to identify who they are so that you process their data in accordance with the GDPR legislation.
What are the rules on marketing calls?
You can call any business that has specifically consented to your calls – for example, by ticking an opt-in box.
You can also make live calls to any business number that is not registered on the Telephone Preference Service (TPS) or the Corporate TPS (CTPS), but only if they haven’t objected to your calls in the past.
You should remember that some businesses (sole traders and some partnerships) register with the TPS, and others (companies, some partnerships and government bodies) register with the CTPS. For business-to-business calls, you will therefore need to screen against the TPS and the CTPS registers, as well as your own ‘do not call’ list.