Indian passport holders need a visa for Morocco. There is no visa on arrival. Most guests use the electronic visa, which is applied for online and usually returns within one to three working days, and an invitation letter from the organiser in Morocco is accepted as proof of purpose.
What each guest needs
A passport valid for at least six months beyond the date of entry, with two blank pages. Recent passport photographs. A confirmed return flight. Proof of accommodation, which for a wedding party is usually the hotel block confirmation. And the invitation letter.
Applications go through the official Moroccan e-visa portal, or through a consulate in India if a guest prefers or is not eligible for the electronic route.
The invitation letter is the part we do
A letter from the organiser in Morocco, naming the guest, the event, the dates and the accommodation, is accepted as proof of purpose. We issue one per guest rather than a single generic letter, with the venue confirmation attached.
Generic letters get questioned. A letter with a named guest, a named venue and matching dates does not.
Timing, and the guests who leave it late
Tell guests at save the date stage, not with the formal invitation. Six months out, in writing, with the checklist.
Then tell them again at three months, and once more at six weeks. Some proportion of any guest list will still be applying a fortnight before. Building a two week buffer into the advice is more effective than assuming people will act on the first email.
Other passports in the party
A wedding of this kind rarely has one nationality in it. British, American and most EU passport holders enter Morocco visa free for short stays. UAE residents with Indian passports still need the visa, because it follows the passport rather than the residence.
We check each passport against the current rules rather than issuing one blanket instruction, because the blanket instruction is wrong for somebody every time.
What we need from each guest, and when
One passport scan, the spelling of the name exactly as it appears on it, the travel dates and the hotel they are booked into. That is the whole list, and it is what goes into the invitation letter.
Collect it with the RSVP rather than chasing it afterwards. The families who do this in one round finish at six months. The families who do it guest by guest are still chasing four passports a fortnight before, and those four are always the ones who need the visa most urgently.