The name Smyrna comes from bitterness - it was a persecuted church.
The seaside town of Smyrna (Izmir today) was also known as the fragrant port for its commerce of myrrh, from which it derives its name. Myrrh was an ointment, much used in the embalming and preserving dead bodies (John 19:39-40), and was obtained by pressing the wood from which it originates, a picture of the suffering the persecuted church had to endure. Smyrna had a temple dedicated to the goddess Rome, symbol of the Roman emperor.
The Lord Jesus, in his description of himself, gives comfort to the persecuted church, assuring it of his eternity, and reminding it that he conquered death.
Like all other churches, he knows their works, by which he means that he is aware of all that is done within the congregation. He knows their tribulation, a translation of a Greek word which really means pressure, and concerns the repeated aggression coming from the enemies of the Gospel. He is aware that they are short of the things of this world, but they had an abundance of spiritual riches. He also knows the blasphemy of the false Jews, probably a reference to those attending the synagogue, who rejected the Lord Jesus as the Messiah (Romans 2:28-29), uttered libel against the church, and provoked persecution as in Iconium (Acts 14:2), thereby siding with Satan.
Christ has nothing to write against Smyrna. They are urged not to fear the things that they are about to suffer: imprisonment, where their faith will be tested, and persecution for ten days (so they know it is temporary - the Lord is in control). Faithfulness and perseverance will be rewarded with eternal life. For Smyrna this prophecy would be fulfilled shortly after the book of Revelation was written. The cult to the emperor was intensified, and Christians were imprisoned and killed because they refused to sacrifice to him.
The church in Smyrna is an accurate prophecy of the persecutions and sufferings endured by the majority of the Christian churches from 170 AD (Emperor Marcus Aurelius) to 312 AD (Diocletian); the last, and fiercest, persecution was carried out by Diocletian, for a period of 10 years. In all, there were ten great official persecutions of Christians by the Roman emperors, starting with Domitian in 96 AD, when it was made illegal to be a Christian. These persecutions, as naturally happens, had the effect of purifying the churches from non-committed elements, and making them return to the initial love which they had left during the later part of the Ephesian period. During that period, the first zeal had flagged and conformity to the world and its ways had increased, the nicolaitans had began to have their way and an organisation of churches calling themselves catholic, meaning universal, developed. When the persecution intensified, some churches separated from it, and many churches, holding to the original New Testament doctrines and practices in a greater or less degree, gradually found themselves separated from the catholic churches which had largely abandoned them.
In this letter the Lord Jesus gives the assurance that he who overcomes shall not be hurt by the second death, which is eternal separation from God and the lake of fire (chapter 20:14). In the context of the letter, though he may have to endure physical death for his faith, his soul is saved from judgment and eternal punishment.
8 "And to the angel of the church in Smyrna write, 'These things says the First and the Last, who was dead, and came to life:
9 "I know your works, tribulation, and poverty (but you are rich); and I know the blasphemy of those who say they are Jews and are not, but are a synagogue of Satan.
10 "Do not fear any of those things which you are about to suffer. Indeed, the devil is about to throw some of you into prison, that you may be tested, and you will have tribulation ten days. Be faithful until death, and I will give you the crown of life.
11 "He who has an ear, let him hear what the Spirit says to the churches. He who overcomes shall not be hurt by the second death." ' Rev 2:8-11 (NKJV)