Ruling on a woman smiling at Muslim men from other countries to make them feel welcome

Firstly: 

Women should cover their faces in front of non-mahram men,
because of a great deal of evidence that has been quoted in the answer to
question no. 11774. Based on
this, she should not be smiling in this manner in the first place.  

Secondly: 

A great deal of shar’i evidence indicates that it is not
allowed to do that which may cause men to be tempted by women and vice
versa, such as shaking hands, being alone with a member of the opposite sex,
speaking in a soft voice, a woman going out wearing perfume so that its
fragrance may be smelt, a man looking at women and a woman looking at men if
that is with desire. 

See the answer to question no.
84089 for more information on
the evidence concerning that. 

For a woman to smile at a man to be kind to them for the
purpose referred to in the question implies that each of them is looking at
the other, and that is forbidden because Allaah says (interpretation of the
meaning): 

“Tell the believing men to lower their gaze (from looking
at forbidden things), and protect their private parts (from illegal sexual
acts). That is purer for them. Verily, Allaah is All‑Aware of what they do.

31. And tell the believing women to lower their gaze (from
looking at forbidden things), and protect their private parts (from illegal
sexual acts) and not to show off their adornment except only that which is
apparent (like both eyes for necessity to see the way, or outer palms of
hands or one eye or dress like veil, gloves, headcover, apron), and to draw
their veils all over Juyoobihinna (i.e. their bodies, faces, necks and
bosoms) and not to reveal their adornment except to their husbands, or their
fathers, or their husband’s fathers, or their sons, or their husband’s sons,
or their brothers or their brother’s sons, or their sister’s sons, or their
(Muslim) women (i.e. their sisters in Islam), or the (female) slaves whom
their right hands possess, or old male servants who lack vigour, or small
children who have no sense of feminine sex. And let them not stamp their
feet so as to reveal what they hide of their adornment. And all of you beg
Allaah to forgive you all, O believers, that you may be successful”

[al-Noor 24:30-31]

This smiling may have an effect on the heart that is not less
than the effect of soft speech, and it may lead to the fitnah (temptation)
that Allaah has warned against when He said (interpretation of the
meaning): 

“O wives of the Prophet! You are not like any other women.
If you keep your duty (to Allaah), then be not soft in speech, lest he in
whose heart is a disease (of hypocrisy, or evil desire for adultery) should
be moved with desire, but speak in an honourable manner”

[al-Ahzaab 33:32]

The Standing Committee for Issuing Fatwas was asked: What is
the ruling on a woman who smiles in front of a non-mahram man, but without
showing her teeth and without making any sound? 

They replied: 

It is haraam for a woman to uncover her face or to smile at a
non-mahram man, because of the evil to which that leads. And Allaah is the
Source of strength. May Allaah send blessing and peace upon our Prophet
Muhammad and his family and companions. End quote. 

The Standing Committee for Academic Research and Issuing
Fatwas. 

‘Abd al-‘Azeez ibn ‘Abd-Allaah ibn Baaz, ‘Abd al-Razzaaq
‘Afeefi, ‘Abd-Allaah ibn Ghadyaan. 

End quote from Fataawa al-Lajnah al-Daa’imah (17/25).

With regard to the Muslims from other countries whom you
mention, the Muslims should honour them, make them feel welcome and take
care of them, without doing anything that is haraam. Men should take care of
men and women should take care of women. You will find many Muslim women who
need your care and kind treatment. 

May Allaah increase us and you in guidance. 

And Allaah knows best.