Rabbi Shlomo Aviner answers hundreds of text message questions a day! Here's a sample:
Q: Is it permissible to point out that it is April First and participate in its customs?
A: No. It is the Christian date. And it is also involving oneself with nonsense.
Non-Jew at the Seder
Q: Is it permissible to invite a non-Jew to the Pesach Seder?
A: There is in fact a prohibition against inviting a non-Jew on Yom Tov, since it is forbidden to cook for a non-Jew on Yom Tov. Our Sages made a decree against inviting a non-Jew lest one add food for him while cooking (Shulchan Aruch, Orach Chaim 512:1. Mishnah Berurah ibid.). However, our Sages did allow a non-Jew to attend in certain situations when a Jew would not cook for the guest, i.e. when he came on his own, after the meal was already prepared. And all the more so in our time when everything is ready in advance and we do not cook at all after the holiday has begun. It is certainly permissible for a foreign worker to eat, since he is similar to a servant who may eat (see Rama, Yoreh Deah 113:4). And our Rabbis were also lenient in various areas for a non-Jew in the process of conversion (Shut Minchat Eleazar 3:8). And see the commentary of the Ya'avetz on the Haggadah, who explains the words "All who are hungry, come and eat" as an invitation to non-Jews. And see Moadei Ha-Re'eiyah (p. 320) that the non-Jewish British Governor of Jerusalem attended the Seder of Maran Ha-Rav Kook. Ha-Rav Moshe Feinstein also writes that there is no problem in teaching Torah to Jews when a non-Jew will also hear, as in the case of Rabban Gamliel and his non-Jewish servant Tavi, who in doing so became quite knowledgeable in Halachah. But one should obviously be careful about a non-Jew touching the wine if it is "Eino Mevushal" (Shut Igrot Moshe, Yoreh Deah 2:132).
Q: Should one sign up for the Korban Pesach in anticipation of the coming of the Mashiach?
A: No. There is no need. We anticipate the coming of the Mashiach every day, but the building of the Temple will not be today. See Rambam, Melachim 1:2.
Selling Chametz over the Internet
Q: Is it possible to sell Chametz over the internet?
A: Yes. It is a form of appointing an agent.
Q: How do we agree to have the wicked son at the Seder and talk to him?
A: Because he is our son, and we are happy that he is present. The true tragedy is the fifth son who is not even there.
Ashkenazi eating at Sefardi's House
Q: I am Ashkenazi. It is permissible for me to spend Seder night at the house of a Sefardi, who eats Kitniyot?
A: Yes, but don't eat Kitniyot. It is permissible, however, to eat: food which touched Kitniyot, food which absorbed Kitniyot, food in which the Kitniyot are no longer recognizable and are nullified in a majority, and food cooked in Kitniyot pots and pans (Shut She'eilat Shlomo 3:141).
Pesach Sacrifice of the Samarians
Q: Is there a problem with going and seeing the Pesach sacrifice of the Samarians?
A: It is certainly forbidden. After all, it is heresy. One who attends is strengthening those who are committing a transgression.
Medicine for Pesach
Q: Does medicine require Pesach certification?
A: All medicine which lacks taste is Kosher for Pesach and the rest of the year.
Soft Matzah for Ashkenazim
Q: Is it permissible for Ashkenazim to eat soft Matzah, like the Sefardim eat?
A: There are those who forbid it. While they agree that in the past Ashkenazim did eat it, they ceased doing so (Ha-Rav Shlomo Zalman Auerbach, Halichot Shlomo chap. 9 note #80) and there is no tradition (Masoret) to permit it. But there is also no tradition to forbid it, and the Rama (Orach Chaim 460:4) mentions that the Matzot where thick (and must therefore have been soft). And the Sha'arei Teshuvah writes there that they would prepare them with a type of grater, which is also a sign that they were soft. Ha-Rav Asher Weiss writes that the basic Halachah is that they are permissible, but he is concerned that we are not experts in making them soft and there is therefore a concern about Chametz (at the end of his Haggadah, siman #15). But Sefardim are experts. And Ha-Rav Herschel Schachter also permits them. In sum: It is permissible.
Q: Is it permissible to use a flashlight for Bedikat Chametz?
A: Yes, but a candle is preferable.
Q: Are empty beer bottles put out for decoration considered Chametz?
Q: Does deodorant require Kosher certification for Pesach?
A: No, since it is inedible to a dog.
Q: What is permissible to sell?
A: Everything. But it is preferable not to sell actual Chametz, like bread, cakes, noodles, schnitzel, etc.
Checking Books for Chametz
Q: Is there an obligation to check books for Chametz?
A: Some are strict, but the basic halachah is that one is not obligated to clean them, as the crumbs that would be within them are smaller than the volume of an olive. Just do not put the books on the table on which you eat. One does not violate the prohibitions of not seeing or finding Chametz with crumbs smaller than the volume of an olive, but it is obviously forbidden to eat them, and if they fall into food, they are not nullified, even by a thousand-to-one ratio (Haggadah Chazon Ovadiah of Ha-Rav Ovadiah Yosef, p. 21).
Q: Is fish food Chametz?
A: Some is and some isn't. Ask in the pet store for non-Chametz fish food.
Q: Are cigarettes Chametz?
A: No. But they are forbidden all year round.
Brushing Teeth after Afikoman
Q: Is it permissible to brush one's teeth after the Afikoman or is it forbidden because it removes the taste of the Afikoman?
A: It is permissible, just as it is permissible – according to most authorities – to drink coffee and tea after it, since only food is forbidden and not drink.
Moshe in the Haggadah
Q: Why isn't Moshe mentioned in the Haggadah?
A: In order to make it clear who provided the salvation – the Master of the Universe. I and not an angel, I and not a messenger. In most versions, Moshe Rabbenu is only mentioned in passing: "And they believed in Hashem and Moshe, His servant." In truth, Hashem provided the salvation, and Moshe Rabbenu is His servant.
Hand-Made or Machine-Made Matzah
Q: According to Ha-Rav Tzvi Yehudah Kook, which is preferable: hand-made or machine-made matzah?
A: Our Rabbi was particular to use machine-made matzah since it was decided by the halachic authorities that machine-made Matzah is kosher, and there is, in fact, greater care regarding the concern of Chametz than with hand-made Matzah (and once when our Rabbi was asked this question, he answered: In the same amount of time that we exert ourselves to make one hand-made matzah it is possible to make Reb Noson’s [our Rabbi’s brother-in-law], his and many other people’s matzah for the entire holiday).