Burns Philp Line letterhead in one of these covers.

J.F. Newman came to the New Hebrides in about 1904/05. He was on the Burns Philp & Co. steamer TAMBO which left Sydney on 1 December 1905. His son Oscar (well known in the New Hebrides) was born in 1907, his first daughter Olive (later called Olub) in 1908 and later his second daughter Thora.
All these Malmberg letters above from reg.-no. from 445 to 456 (or even more) were written I suppose on board the MAKAMBO (Burns Philp & Co.). The Makambo left Sydney on 1 March for Lord Howe Island, Norfolk Island and the New Hebrides. She made the usual run through all the islands and returned to Sydney on 23 April. The covers are backstamped Sydney, April 24.
On 8 May 1911 Frank Malmberg left Sydney to Vancouver on the R.M.S. Marama (Canadian-Australian Royal Mail Line) according to a notice in the Sydney Morning Herald.

Some information about
Malmberg - (new 2/2019)

Malmberg

Registered cover to Sydney. The mixed language stamps cancelled with Type 7. (Goron coll.)

Registered cover to Halifax, England. The five 2½d stamps from the 1908 British issue are cancelled with PCH type 5. Backstamped Sydney 23 August 1911 and London 29 September 1911. (ex Jersey coll., now ???)

Registered cover to Halifax, England. The 2d and 6d stamps from the 1908 British issue are cancelled with PCH type 5. Backstamped Sydney 23 August 1911 and London 29 September 1911.
Image thanks to David Moss and Northwich Philatelic Society | Northwich, Cheshire.

Registered cover with a mixed franking of 5+10c French stamps and 1+2½c Edward VII, Cancelled "PORT-VILA NELLES HEBRIDES 7 AOUT 11". It shows the non-colonial letter rate of 2 1/2d (25c) and a registration fee of 2 1/2d (25c) Transit and arr.pmks on back (unknown dates). (unknown coll.)

Letter in this cover from Mr. A. Deschamps, the second condominium postmaster:

I answer to your letter of 26th April 1911 and send you 4 letters R (registered?) without the 5th. I stored one letter on which is affixed a 0,25 F French Condominium stamp. This stamp is not yet valid here as these have not been sent from France. I'll send you this letter directly when I can. My best wishes, A. Deschamps.

Registered cover to Coffs Harbour, N.S.W., two French 1908 25c stamps and the 10c and 50c of the French 1910 issue cancelled with PCH type 5. Stamped Coffs Harbour 28 AU 11. ("Mele" coll.)

Registered cover to Coffs Harbour, N.S.W. with a couple of British stamps. (unknown coll.)

Cover front with mixed frankings: the French issue 10c pair, the French 25c and the British 2½d stamps cancelled with PCH type 5, registration mark R1 applied below the stamps. The cover was sent to Sydney and may have been a double weight cover. ("RMD" coll.)

Registered to New Zealand. The 5d and 6d stamps cancelled with Goyns-Klinger type PM2. Registration cachet type NR1C. Registered colonial letter rate per ½ oz. was 2d and registration 2&fec12;d - possibly a heavy letter and still a bit overpaid. TPO/NZ/MAINTRUNK AK (OUT) b/s with s/r WESTPORT and BURNETTS FADE arrival marks from being re-forwarded.
Image thanks to Steve Drewett stamps.

Registered cover to Liverpool, England. The complete set of stamps from the 1908 British issue is cancelled with PCH type 5. We see a 1/- multiple crown CA watermark! ("Mele" coll.)

Buess cover to Germany. 2 x 6d and a 1/- cancelled with Goyns-Klinger type PM2. Registration cachet type NR1C. Image thanks to Steve Drewett stamps.

English 1908 1d and 2½d together with a French 25c stamp make a total of 60c for this registered letter to Australia. 25c registration and three pence halfpenny for double weight? I don't know. Cancel is PCH type 7 with an unusual grave accent on the E of DE. Cancelled on arrival at Coff's Harbour on 29 December 1911. Normally a red pencil cross means "Express Letter", a blue one "Registered". I don't know why this one and one other one to Gilles have a red cross. (Goron collection)

The 1908 French set on a cover to Australia cancelled with PCH Type 7 ("Aore" collection)

Registered letter (front) to NSW, 50c paying letter rate (20c) and registration rate (25c), overpaid 5c. Boxed type R1 handstamp, cancel Type 5 and Coffs Harbour (29 Dec 1911) receiving cancel. (Ruecker coll.)

Another Gilles cover: complete 1908 French set cancelled with PCH type 7. According to the registration numbers there could be more of them. (Seen on Ebay in June 2006)

A late cover with the British 1908 issue:
Registred letter from Vila to London with the ½d (W. CA simple), 1/2d (W. CA multiple), 5d, 6d, and 1s. stamps cancelled with PCH type 5A (the one with the inverted 2). Backstamped Sydney 20 JA 12 in transit and at arrival in London 25FE12.("SeSi" collection).

1912 and later covers of the 1908 provisional issue

A late cover with the British 1908 issue:
Registred letter from Vila to London with the ½d (W. CA simple), 1/2d (W. CA multiple), 5d, 6d, and 1s. stamps cancelled with PCH type 5A (the one with the inverted 2). Backstamped Sydney 20 JA 12 in transit and at arrival in London 25FE12.("SeSi" collection).

Registered letter with three 25c stamps of the 1908 French series with the typical 1912 rotated 2 cancel, backstamped in Sydney and Ulm (23 MRZ), with an additional cancel on the front which is the mirror inverted copy of the Ulm arrival cancel from the next letter.
This is a late "Kiderlen" letter. There are many earlier ones to (from) him, 1894 Labuan or 1898 Western Australia for instance. (Klinger coll.)

Another "Kiderlen" cover, registration number 220. Backstamped Sydney 19 February 1912 and Ulm March 23, 1912. The cover must have been in an exhibition in France or Belgium: for some time it was not allowed there to present covers with the name of the addressee, it therefore is erased. ("SeSi" collection).

Another "Kiderlen" cover, registration number 223. Backstamped Sydney 19 February 1912 and Ulm March 23, 1912. (44 days). ("JGI" collection).

Registred letter from Vila to Ulm, Germnay with three French 25c stamps cancelled with GK type PM2 (the one with the inverted 2 in (19)12). Backstamped Sydney 19 February 12 in transit and at arrival in Ulm on 23 March 1912. (Klinger coll.).

reverse

Registred letter from Vila to Ulm, Germnay with two French 25c stamps cancelled with GK type PM2 (the one with the inverted 2 in (19)12). Backstamped Sydney 19 February 12 in transit and at arrival in Ulm on 23 March 1912. Maybe this one had an erased address name too like the one above and somebody restored it with a wrong name or didn't find "Kiderlen" so positive. (Seen on Delcampe).

A very late cover to England with the British 1908 issue. The 1d and 2½d stamps cancelled with PCH type 5. ("Mele" coll.)

Letter to Germany, 25c seems to have been the correct rate to not French/British Europe. PCH type 5. ("Aore" coll)

Registered letter to Switzerland, the 1908 - 1910 mixed British postage cancelled with Type 5. (unknown, coll.)

Registered "Tuck's Post Card" to Wolfersdorf, Austria. Longf message non-colonial postcard rate in 1913 was 1d and registration fee 2½d so this card is correctly franked. Cancelled GK type PM2.
Image thanks to Steve Drewett Postal History

Letter to Belgium, 25c letter rate too, PCH Type 5, circular Belgian postal service handstamp on front, backstamped with Sydney machine cancel on May 23 and on arrival Brussel/Bruxelles June 29, 1913. The cover arrived in Sydney on 22 May with the MALAITA. (Klinger coll)

23 July 1962
(new 2/2019)

A rather late use: a 1910 25c stamp on a cover to Canada, not taxed this time. (See 1925 postal history used 1937 & later - at bottom and 1941 postal history) Handstamped "Nouvelles - Hébrides / Délégation Française / T A N N A." This cover is from the French District Agent (FDA) on Tanna. At that time, Tanna didn't have it's own cancel, so everything got cancelled in Vila.
Image thanks to Sandafayre Stamp Auctions