1.
if you don't mind; if it's not a problem; if it's okay with you
A polite expression used to preface a request or question, showing consideration for the other person's circumstances. Implies that the speaker will accept a refusal. Very common in polite and business Japanese.
Usage
A polite set phrase used to soften requests and personal questions. Very common in business emails, customer service, and formal conversations. The base form is 差し支える (to be inconvenient/problematic), and なければ is the conditional negative (if not). Can also appear as 差し支えなかったら (slightly less formal) or 差し支えございませんでしたら (very formal/humble).