Online stores suggest their customers to change their passwords periodically.

The structure used here is subject + suggest + object + to + V1. Instinctively I know that’s not right, but to find out why I headed over to Netspeak.org and this is what I found:

• subject + suggest + object + to + V1
  [no results – must be wrong.]
• subject + suggest + object + V1
  [plenty of results – must be correct!]
• subject + suggest + that + object + V1
  [also possible!]

So, we can say..

• Online stores suggest their customers change their passwords periodically.
• Online stores suggest that their customers change their passwords periodically.

And when I looked for other patterns at Netspeak.org I noticed another structure:

• Online stores suggest changing passwords periodically.
  subject + suggest + __ing

Alternatively, if you really love using ‘to + v1’ then you can use advise instead of suggest:

• Online stores advise customers to change passwords periodically.

Netspeak.org

What a fantastic resource for investigating the way words fit into different grammatical structures! Follow the search strategies ‘suggested’ at Netspeak.org and explore for yourselves!