More than 55,000 Canada Post workers could go on strike later this week, bringing mail and parcel deliveries to a halt.

Here’s what you need to know.

When does the strike begin?

According to a strike notice, postal workers plan to hit the picket lines starting at midnight on Friday, May 23.

However, Canadian Union of Postal Worker (CUPW) negotiator Jim Gallant told CTV News in an interview that they would delay the strike notice by two weeks should the company deliver a new offer on Wednesday.

Canada Post spokesperson Jon Hamilton confirmed to CTV News there would be a meeting with the union at that time.

Will you still get mail and parcels?

That depends on if there is a national labour disruption or smaller rotating strikes.

In the event of a national labour disruption, mail and parcel delivery will cease across Canada once the strike begins on Friday. New items will also not be accepted until the strike ends, and those that haven’t been delivered yet will be held back.

If there are smaller rotating strikes, mail and parcel services will only be interrupted in affected areas, but customers nationwide may still experience delays.

A Canadian Union of Postal Workers spokesperson tells CTVNews.ca that a final decision on this has not been confirmed.

Are there any exceptions?

Social assistance cheques will continue to be delivered, even if there is a national strike. The same goes for live animals, although new animals will not be accepted in affected areas or until the strike is over.

What if I still need to send something?

Private courier companies like FedEx, Purolator, UPS, DHL and Canpar will still be operating, although they can be more expensive than Canada Post. Rideshare companies like Uber and Lyft offer local parcel delivery. Smaller delivery companies and bike couriers can also be found in many Canadian cities.

Didn’t postal workers already go on strike?

The latest job action will be the second strike by Canada’s postal workers in six months. A 32-day strike in November and December saw millions of parcels and letters held up during the busy holiday season. The strike ended after federal intervention.

Why are postal workers striking again?

Sticking points include Canada Post’s desire to hire part-time workers for weekend deliveries, which the union opposes. Full-time postal workers currently get overtime pay for weekend work. Other outstanding issues include worker pay, benefits and pensions. Although it appears unlikely, an agreement between the union and Crown corporation could still avert a strike this week.