I am submitting to you our contract renewal proposal.
'Sottopongo' = sot-to-PON-go; 'tt' shortens the preceding vowel.
Use when presenting a contract renewal to an existing client, typically 30–90 days before the current contract expires.
'Sottoporre' (to submit/present for consideration) is a formal verb implying respectful deference to the other party's judgement. It is more elegant than 'le mando' (I'm sending you). 'Rinnovo contrattuale' is the standard term for contract renewal in Italian business.
Le proponiamo il rinnovo del contratto alle condizioni seguenti.
We propose the renewal of the contract on the following conditions.
More direct; starts with the offer
Il nostro contratto scade il [data]; desideriamo rinnovarlo.
Our contract expires on [date]; we wish to renew it.
States the expiry date clearly
In vista della scadenza contrattuale, le invio la nuova proposta.
In view of the contract expiry, I am sending you the new proposal.
References the upcoming deadline
In Italy, many commercial contracts (especially for services and leases) renew automatically ('tacito rinnovo') unless one party gives formal written notice of cancellation within a specified period. Always check the contract terms.