Is it permissible to limit interaction with female colleagues to greeting them, asking about their well-being, and inviting them to Allah, and is it permissible to check on them by phone, and if that is not permissible, is it then permissible to check on them and congratulate them on occasions through their brothers?

Great caution must be exercised when dealing with women, as the temptation of women is among the most harmful temptations. Islamic law prohibits something and blocks the means leading to it. This includes prohibiting looking at women, being alone with them, a woman traveling without a mahram, and her displaying her adornments (tabarruj). Scholars have forbidden speaking with a young non-mahram woman without necessity, as it is a potential source of temptation. Therefore, one should refrain from conversing with female colleagues and being overly familiar with them, as a way of blocking off means (to sin). However, inquiring about their well-being and congratulating them on occasions through relatives is permissible, provided that the heart remains detached.