This is the part of the email we received from Havana
At the interview, you should submit recent evidence to prove that your spousal relationship with your sponsor is genuine and still ongoing. Such evidence may include:
i. Correspondence between you and your sponsor such as: letters with their original post-marked envelopes, printouts of e-mail messages, chat records, faxes, etc. (whatever has not been submitted yet).
ii. Telephone bills indicating calls between you and your sponsor (whichever has not been submitted yet). DO NOT submit phone cards, unless accompanied by an itemized statement from the phone-card company.
iii. Photographs of you and your sponsor together, (whichever has not been submitted yet). The photographs must be printed. DO NOT bring photographs in electronic devices such as CD's or USB memories.
iv. Evidence of financial support between you and your sponsor (whatever has not been submitted yet).
v. Any other evidence that you would like the immigration officer to consider and that might be useful to demonstrate the genuineness of your relationship with your sponsor.
The day of the interview, you should arrive at least 5 min in advance. At the Immigration gate, you will explain that he has an appointment for an interview. Please remember you must bring your passport and your dependent`s passports, if applied.
Please confirm your attendance by replying to this email.
Cordially,
Immigration Section