Reports coming in from picket lines suggest a solid response from postal workers, with near 100% turnout in Bromley By Bow and Nine Elms, London, few in at Bristol and similarly tiny numbers crossing lines at Middlesborough.
Photographers have been down at Mount Pleasant and Bromley by Bow sorting offices, where they report good spirits from the strikers despite the early start and very few people crossing the picket lines.
At Mount Pleasant freelance Jonathan Warren caught one manager on camera throwing the post into the back of his Audi and union deputy general secretary Dave Ward showed up once it was light to talk to strikers.
Guy Smallman meanwhile was down at Bow, where he says there was a 100% solid strike.
On the Urban75 bulletin board, 4thwrite said the response has been positive: "Just got back from the Middlsbrough picket. Only a tiny number had gone in and there was a pretty good response off the vans going past. The office is pretty central but just off the main road so you don't get many people walking past, but those that did were pretty supportive."
At Bristol, it was reported that 7 out of 400 staff had crossed in the early morning, with strikers in fairly good spirits.
Portsmouth sorting office has counted it at 194 out of 197.
The Guardian has suggested that at Birmingham there has been a "steady flow" of mail vans with about 40 on the picket, though it is not explained whether this is mostly made up of managers.
NOTE: These are only initial impressions from people at the picket lines. Updates should be forthcoming