Is the agreement between spouses to limit conversations with non-mahrams to merely returning greetings, in order to avoid temptation, considered a lack of respect or contrary to religion?

There is no doubt that avoiding strangers is essential for one's safety from temptations. The Prophet, peace and blessings be upon him, warned about the danger of the temptation of women. A Muslim must abide by the Sharia (definition), avoiding the forbidden and permitting the permissible. It is permissible for women to address men when there is no fear of temptation and without softening the speech, as Allah Almighty says: "So do not soften your speech [to men], lest he in whose heart is disease should covet, but speak with appropriate words." One must be careful of harassment from immoral people on the phone, and advise the wife not to answer anyone she does not know, and adhere to appropriate speech when addressing brothers, and cut off communication if they do not abide by the Sharia. The husband must also adhere to Islamic etiquette when addressing his female neighbors.